Search

In this paper, we examine the shape effects of different nanoparticles of an incompressible, unsteady flow of a nanofluid Al 2 O 3 with water H 2 O as the base fluid over a rotating disk. Magnetic field results are also added. In this research, four distinct shapes of Al 2 O 3 nanoparticles, i.e., sphere, blade, cylinder and brick, have been employed. Every shape is suspended at the same volume. After using the Von Karman transformation, the Navier–Stokes equation, along with the magnetic field effect and the thermal energy equation, is numerically solved by using the bvp4c MATLAB solver. The effects of various parameters on the velocity field and temperature profile are illustrated graphically. This analysis is validated by comparing it to the previously described research. Furthermore, increasing the volume fraction parameter 0 ≤ ϕ ≤ 0. 1 % causes the radial, tangential, and axial velocities near the disk for the shapes brick, cylinder, and blade to decrease and increase for the shape sphere. The fluid rotating in front of the disk rotates more slowly for small values of the unsteadiness parameter α ̂. The magnetic field M has a significant influence on the axial flow when the suction parameter values are small, but this impact is limited when the suction parameter values are large. [ABSTRACT FROM AUTHOR]

A liquid piston Stirling engine is an external combustion engine that uses air and water under atmospheric pressure as its working fluids. Resulting from its uncomplicated design and the capacity to operate under relatively low temperature differentials of less than 100 °C, it has attracted considerable attention in recent years. This paper presents the fundamental characteristics of the liquid piston engine combined with a self-rectifying turbine for the advancement of thermal generators. When the turbine is installed in the water region rather than in the air region, it exhibits unidirectional rotation with a rotational speed directly proportional to the velocity amplitude of the reciprocating axial flow. Additionally, the acoustic impedance within the duct section containing the turbine is determined, demonstrating that the real part of impedance rises with increasing axial velocity, indicating a loss mechanism similar to the minor loss. Furthermore, the installation of the turbine results in a breakdown of symmetry in the engine oscillation mode. To maintain symmetry and improve system design, future developments must consider the installation of a turbine in each unit. These findings can pave the way to the design of liquid piston Stirling engines and their applications in thermal energy conversion. [ABSTRACT FROM AUTHOR]

Among the design requirements of hypersonic vehicles, reducing aerodynamic heating and drag force simultaneously is the main challenge. This paper proposes a novel spike aerodome-channel combination concept to realize the flow field reconstruction around the hypersonic blunt body. The novel configuration is investigated in the axisymmetric flow at a Mach number of 6 at zero angle of attack. The two-dimensional Reynold-averaged Navier–Stokes equations are numerically solved, and the shear-stress transport k–ω model is the turbulence model implemented in this study. Parameters such as spike length and lateral jet location are investigated to explore the drag and heat reduction performance and the flow control features. The obtained results show that the application of the novel spike aerodome-channel concept alters the flow field by eliminating or replacing the strong bow shock wave, and the design of hypersonic vehicles can benefit from the application of the proposed concept. The blunt body coupled with a frustum of cone-tipped spike-channel configuration provides a remarkable drag reduction effect of 20.71% with respect to the case without channel. Considering the effect of lateral jet location, the drag reduction performance of the case with LR = 0.75 is superior to that of the root jet case at the same spike length, and a considerable drag reduction of 28.93% is obtained with L/D = 2.4. In addition, longer spike length is beneficial for improving drag reduction performance, while excellent efficiency of heat protection is obtained in a certain spike length range. For the case of L/D = 1.6 with root jet, the peak Stanton number is significantly decreased by 33.51%. [ABSTRACT FROM AUTHOR]

An axial flow circulating pump (AFCP), as a key facility of the large vessel power system, is designed for conveying cooling water of the power system. The pump will be rotated actively under the drive of motor when the vessel is navigated at a low speed, which is called the pump operating condition (POC). Besides, it will be rotated passively under the drive of Inlet flow fluid energy in the case of the vessel at a high speed, which is called the unpowered driven condition (UDC). It is worth noting that the characteristics of internal flow, energy generation and dissipation laws of the AFCP are varied under UDC and POC. This paper analyzes the energy transfer laws of the AFCP under UDC and POC using the modified PANS model and energy conveying theory. Pressure propulsion power (accounting for 82.6%) is a primary factor affecting energy conveying, while Lamb vector divergence and enstrophy (accounting for 17.4%) have limited effects on energy conveying, according to the research findings. Moreover, more intense energy generation and dissipation can be found under UDC with a rising proportion between Lamb vector divergence and enstrophy. [ABSTRACT FROM AUTHOR]

The material most commonly used to filter and clean the intake air of vehicle internal combustion engines is pleated filter paper, which in most cases is shaped in the form of a cylinder or panel. The production technology has a low cost and is not complicated. In addition to high separation efficiency and filtration performance, pleated filter media are required to have low initial pressure drop, which depends on the geometry of the bed. Much research has been conducted in this area. Dust accumulated in the filter bed causes an increase in pressure drop, which is the cause of deformation and sticking of pleats. The lack of stability of the pleats, the need to strengthen them, and the need to obtain small sizes while achieving high efficiency and accuracy of filtration of engine intake air was the reason for the development of a different design and a new technology for making filter cartridges called PowerCore. The distinctive feature of these filters is axial flow in one direction of the air stream, which avoids turbulence and thus minimizes pressure drop. This paper presents a comparative analysis of a standard PowerCore and PowerCore G2 filter bed and two cylindrical filters with a pleated filter bed made of cellulose and polyester. The conditions and methodology of experimental testing of filters with test dust are presented. During the tests, the characteristics of separation efficiency and filtration performance, as well as pressure drop as a function of the mass of dust retained on the filter of two PowerCore filters and two cylindrical filters were performed. Three specimens of test filters with the same filtration area were made from each sample of filter bed. The results showed that in each test of the filter bed, there is an initial filtration period characterized by low (96–98%) initial separation efficiency and the presence of large (dpmax) dust grains. As the dust loading of the bed increases, the separation efficiency and filtration performance obtain higher and higher values. The initial period of filtration ends when the conventional value (99.9%) of separation efficiency is reached. The duration of this period depends on the type of filter bed and for the PowerCore G2 filter ends for a dust loading of km = 33.1 g/m2, and for the cellulose filter for km = 117.3 g/m2. During the initial period, the air behind the PowerCore G2 filter contains grains with sizes in the range of dpmax = 9–16 µm. Behind the cellulose filter, dust grains are much larger, dpmax = 17–35 µm. The total operating time of the PowerCore G2 filter, limited by the achievement of the permittivity resistance Δpwdop = 3 kPa, is twice that of the other filter compositions tested. [ABSTRACT FROM AUTHOR]

In this paper, we have analyzed the bifurcation of stagnation points in the non-Newtonian flow of the FENE-P fluid through a channel induced by peristalsis. The stream function for the flow under consideration is developed under negligible inertia and streamline curvature effects. A nonlinear autonomous system is developed for scrutiny of the critical points. A dynamical system approach is used to examine the stability of bifurcation points. Streamline patterns, and local and global bifurcation diagrams are plotted for analysis of the backward flow, trapping, and augmented flow regions. The impacts of important embedded parameters, i.e., extensibility parameter and Deborah number on local and global bifurcation diagrams, are also examined. The whole analysis reveals that two critical conditions appear in the flow field that are actually responsible for the conversion of backward flow to trapping and trapping to augmented flow. It is further seen that bifurcations occur at lower flow rates for increasing Deborah's number while an opposite trend prevails for increasing the extensibility parameter. A comparison of bifurcations between planar and axisymmetric flows is also performed. It is observed that a greater area of the trapping region is encountered for axisymmetric flow than that for planar flow. [ABSTRACT FROM AUTHOR]

It is traditionally believed that in a liquid of uniform density, an axisymmetric barotropic flow with solid-body rotation is stable. Within the framework of a two-level quasi-geostrophic model, this work shows that this is not in the case of a baroclinic flow with solid-body rotation of the heton type. Such a flow has different directions of rotation at two levels. Due to the vertical velocity shift, this flow is always unstable. This paper develops a linear theory of the instability of such flows both in a model without friction and in a model with Ekman friction. It is shown that, for instability in a model with friction, the horizontal wave number of the disturbance should not exceed a certain critical value. It has been established that instability with respect to longwave disturbances in the model without friction is absolute in nature; i.e., it always exists. The development of instability may be associated with the formation of observed disturbances in the axial zone of intense atmospheric vortices. [ABSTRACT FROM AUTHOR]

Vortex breakdown in a pump sump is a complex and negative factor for the pump. Different from my previous study that focused mainly on the development process of vortex and its damage to the pump, this paper is from a new perspective that studies the energy dissipation and time–frequency characteristics induced by vortex breakdown. The tested data of pressure and velocity in the process of vortex breakdown were obtained by the model. Considering the gas–liquid two-phase flow of the vortices, a new numerical simulation approach is conducted and verified. The results show that the development rules of vortex breakdown reveal that the breakdown is initiated near the blade. The residual disturbance in the flow field continues to propagate after vortex breakdown, inducing unstable flow inside the runner and causing additional energy dissipation. The time–frequency characteristics induced by vortex breakdown indicated that the runner rotation speed has a significant effect on the vortex breakdown. The frequency of vortex breakdown is relatively small under high-speed rotation. Through discussion, it can be concluded that in order to reduce the harm of vortex breakdown, it can take measures such as controlling the impeller rotation speed, stalling anti-vortex measures, and adjusting operating conditions. [ABSTRACT FROM AUTHOR]

This paper presents numerical simulations of the Taylor vortex flow under the influence of an externally applied alternating axial mass flux (through-flow) in a Taylor–Couette system with axial periodic boundary conditions. Such an axially modulating flow can lead to a significant variation in the onset of primary instabilities. Depending on the system parameters, the effect can be both stabilizing and destabilizing, i.e., shifting the bifurcation threshold to larger or smaller control parameters, respectively. It is found that the system response around the primary instability is sensitive to and critically influenced by an alternating mass flux, particularly the modulation frequency. We show that such an alternating axial flow represents an easily and, more importantly, precisely controllable key parameter to change the nonlinear system response from subcritical to supercritical behavior and vice versa. Furthermore, we observe different parameter regimes with regular and irregular intermittent flow dynamics. [ABSTRACT FROM AUTHOR]

Chemical gradients that run axially in a microfluidic channel often contain undesirable high-frequency concentration variations, or noise, that results from mechanical and thermal fluctuations in the system. In this paper, we describe a passive microfluidic component called an ‘expansion channel’ (EC), that removes high frequency noise through axial dispersion. We show that the behavior of the filter can be modeled analytically, using an expression for the transfer function of the microfluidic channel, derived by Xie et al.(Y. W. Xie, L. Chen and C. H. Mastrangelo, Lab Chip, 2008, 8, 907–912). The use of ECs to remove noise from gradients formed in enyzmatic assays in a microfluidic channel is demonstrated. The resulting data quality is improved which enables better fits to chemical models and more accurate analysis. ECs should be very effective in removing noise from axial concentration gradients found in many microfluidic applications, e.g.liquid chromatography, biochemistry, and chemotaxis studies. [ABSTRACT FROM AUTHOR]

As the core component of the flow-making system, the circulating pump has differences in its internal flow structure under different operating conditions, which affects the flow quality of the environmental simulation test area and the authenticity of marine environmental simulation. To explore the internal flow characteristics and outlet evolution characteristics of the circulating pump, this paper uses the DDES (delayed detached eddy simulation) method for numerical simulation. This paper combines BVF (boundary vorticity flow) diagnosis and the limit streamline method to analyze the evolution characteristics of the unstable flow area on the blade surface; it uses the Q criterion to identify the vortex structure inside the pump and analyze its evolution and development laws. Additionally, a quantitative analysis of the flow state of the circulating pump using flow uniformity indexes is performed. The results show that the surface of impeller blades is uniform under 1.0 QN. At 0.7 QN, the evolution process of the blade suction surface BVF is periodic, with a corresponding period of about 2/9 T (0.02 s). At 1.0 QN, the strength and scale of the separated vortices inside the guide vanes are minimized compared to other flow rates, and the scale and strength of the vortices show a decreasing trend along the outer normal direction. The evolution period of the separation vortex on the pressure surface of the guide vane is about 1/3 T (0.033 s) under 1.1 QN and the evolution period of the suction surface of the guide vane is about 2/3 T (0.067 s) under 0.7 QN. The flow uniformity indexes value downstream of the pump outlet under 1.0 QN are very close to the ideal value; with a corresponding value of Ϛi = 0.023, θ ¯ = 89.94°, γ = 0.95, λ = 97.9%, the outflow can be approximately regarded as axial uniform flow. The research results can provide theoretical support for the further optimization design of circulating pumps and lay the foundation for the implementation of real systems. [ABSTRACT FROM AUTHOR]

For a pre-swirl pump-jet propulsor (PJP), the stator inevitably induces the problem of rotor–stator interaction (RSI). In this paper, the mechanism of RSI in a PJP is analyzed through dynamic mode decomposition (DMD). The coherent flow structures and corresponding frequencies have been decomposed and analyzed. The results show that the dominant frequencies of pressure fluctuation in the stationary domain are BPF (rotor blade passing frequency) and its multiples. In contrast, the dominant frequencies in the rotational domain are SPF (stator passing frequency) and its multiples. The frequencies of k*SF (SF, shafting frequency; k = 4, 5, and 8) have also been found. The mode structure corresponding to the SPF is stable and has the highest mode energy. The reconstruction residual formula is introduced, and the axial velocity flow field is reconstructed well by the DMD modes compared with the raw flow field. This research can provide a reference for studying and suppressing RSI in a PJP. [ABSTRACT FROM AUTHOR]

The study focuses on the flow characteristics with geometrical considerations utilizing electrical-conduct Non-Newtonian Fluid. The tubular concentric annulus is the geometry selected for the investigation. The electric-conductive Non-Newtonian Fluid is a character-wise two-constant Bingham model used in this study. The study also utilized geometry, the magnetohydrodynamic (MHD) effect, and the hall current. The employed system had the inner tube spinning and the outer tube stationary. Prandtl's assumptions of boundary layer principles are applied to solve the governing equations using the finite difference method for various fluid flow parameters, the Gauss-Elimination method to compute the results, and the MHD field and geometrical factors with hall current. This paper discusses fluid flow properties such as axial, radial, tangential velocities, and pressure distribution. Further, the mentioned above flow properties impact the heat transfer effect. This research details how flow parameters in the concentric tube flow process affect the development of heat transfer effects in the MHD field and hall current. [Display omitted] • The development of MHD flow and heat transport have been studied computationally. • The impact of Hall current and Magnetic effect on the flow field has been considered. • This work refers to the non-Newtonian fluid as a two-constant yield stress fluid model. • The heat transfer impact has been calculated using the fluid flow properties. • This work has been done using a variety of fluid and geometric factors. [ABSTRACT FROM AUTHOR]

In this paper, we mainly focus on the development of the Taylor-Galerkin/Pressure-Correction method (TG/PC) method to solve the flow of a compressible Newtonian fluid under nonisothermal conditions. The process of development needs applying the two-step Lax–Wendroff method on the energy equation, after which two new steps for energy equations will be obtained within the TG/PC algorithm. In addition, for the density component, the Tait equation of state is adopted to relate density to pressure, which also yields a new step within the novel method to give the correction formula of compressible pressure. To perform the analysis of the new algorithm, Poiseuille flow through axisymmetric rectangular channel for the Newtonian thermal flow is utilized as a simple problem test. The effect of nondimensional factors such as Reynolds number (Re) and Prandtl number (Pr) is discussed in this study. The influence of thermal conductivity (k) and viscosity (μ) on the solution components is presented as well. Also, comparison for both compressible and incompressible flows is provided in addition to a comparison between both cases' convergence, as it turns out that the convergence of the incompressible case is better than the compressible case. All the results of the effects presented in this study agree well with the approved physical trend. [ABSTRACT FROM AUTHOR]

In this paper, a new type of helical blade is introduced, which is designed to minimize the damage of hydraulic turbine to fish. The experiments test the damage for fish under different pressure and pressure gradients. Also, the parameters of the helical blade turbine are optimized based on the damage thresholds. The consequent axial flow turbine features double-blades with a pitch of 2600 mm and a blade envelope angle of 540°. To assess the turbine's impact on fish, an overlapping mesh method is used to analyze the degree of damage to the fish during operation. The findings show that, compared to traditional designs, the application of helical blade turbine significantly reduced the exposure and duration of negative pressure, high pressure gradient, and high shear force. [ABSTRACT FROM AUTHOR]

In this paper, a new theoretical model for the dynamics and stability of a vertical cantilevered aspirating pipe is developed based on the Newtonian method. The effects of the hydrodynamic forces at the free end on the dynamics and stability of the cantilevered pipe are examined in detail. A new comprehensive governing equation is discretized using the Galerkin method. Numerical results are presented to demonstrate the effects of the axial flow velocity ratio, flow angle ratio, and tangential velocity ratio on the eigenfrequency and critical velocity of the cantilevered pipe system. The theoretical model results are also found to be in good quantitative agreement with experimental results. [ABSTRACT FROM AUTHOR]

The complex flow of a supersonic jet (Mach number 2.4–2.5) around the blunt aerodynamic body (consisting of a cylinder with a diameter of 16 mm and a truncated cone) was studied using the high-speed shadowgraph technique and computer vision-based visual data processing. The problem considered is directly related to the rocket and space systems stages safe separation problem in a sufficiently dense atmosphere. For systems with a sequential arrangement of stages, their separation often occurs under the rocket engine jet action. The occurrence of lateral forces in violation of axial symmetry can lead to overturning of the discarded stage and undesirable interaction with the outgoing stage. The goals of the paper were to study the pulsation characteristics of the incoming supersonic jet streamlining the body, as well as the pulsations of the bow shock wave in both axisymmetric and asymmetric flows. The recording frame rate in the experiments was up to 775 000 fps. Computer vision and various machine learning approaches were used to process a large number of shadowgraph images. Canny edge detection and Hough transform, as well as a convolutional neural network (CNN) based on YOLOv2 architecture, were used to automatically track the position of the bow shock relative to the body. Jet sound generation was studied - the amplitude dependence on the distance from the nozzle and the evolution in time. The position of the bow shock relative to the streamlined body and flow pulsations over time were analyzed. Bow shock pulsation spectra at zero angle of attack were compared to those at a small angle of attack (α = 2.5°–3°). The power spectral density was also estimated. The slope of the spectra for the zero angle of attack case was found to be horizontal and the spectra for the small angle of attack case had a slope close to −5/3. The strongest of the measured bow shock frequencies were found to be close to those of the jet mixing layer pulsations. The hardware signal spectrum was also measured and this signal can be considered as noise. The described approach makes it possible to obtain the physical characteristics of the flow at any point of interest. It was also shown that the automation of flow visualization experiments using computer vision techniques allows to increase the speed of data processing and obtaining new physical information, which may be important for engineers developing aircraft and spacecraft technologies. • Supersonic jet flow around a blunt body was studied experimentally and also numerically. • Computer vision tools were applied to supersonic flow investigation. • Spectra of jet generated acoustic waves were determined. • Time dependent bow shock positions were automatically measured by the neural network. • Amplitudes of bow shock pulsations and flow fluctuations depend on the angle of the body relative to the jet direction. [ABSTRACT FROM AUTHOR]

This paper presents numerical simulations of propeller–hull interaction of a ship model for the dynamic condition, demonstrating the ability of the developed self-propulsion module in OpenFOAM. A dynamic motion class has been developed based on the sliding mesh method to simulate a rotating propeller with ship motions. A body-force method is also implemented to simulate propeller–hull interaction to reduce the computational cost of propeller modeling. Validation studies were carried out for the Japan Bulk Carrier (JBC) ship model. The bare-hull resistance, sinkage, and trim are verified against the experimental data. The propeller open-water hydrodynamic characteristics are then computed and validated using sliding mesh and body-force methods. Finally, the self-propulsion simulations are carried out for the JBC model in calm water with sinkage and trim at the design speed. Numerical predictions of the self-propulsion parameters and axial flow velocity distributions at different transverse locations are presented. [ABSTRACT FROM AUTHOR]

This paper deals with one-dimensional axisymmetric quasi-static coupled magnetothermoelastic problems subjected to magnetic and vapor fields. Laplace transform and finite difference methods are used to analyze the problems. Using the Laplace transform with respect to time, the general solutions of the governing equations are obtained in the transform domain. The solution is obtained by using the matrix similarity transformation and inverse Laplace transform. We obtain solutions for the temperature and thermal deformation distributions for a transient and steady state. It is demonstrated that the computational procedures established in this paper are capable of solving the generalized magnetothermoelasticity problem of a hollow cylinder with nonhomogeneous layers. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the singularity near the degenerate points of the steady axisymmetric flow with general vorticity of an inviscid incompressible fluid acted on by gravity and with a free surface. We called the points on the free boundary at which the gradient of the stream function vanishes as the degenerate points. The main results in this paper give the different classifications of the singularity near the degenerate points on the free surface. More precisely, we obtained that at the stagnation points, the possible profiles must be a Stokes corner, a horizontal cusp, or a horizontal flatness. At the degenerate points on the symmetric axis except the origin, the wave profile must be a cusp. At the origin, the possible wave profiles must be a Garabedian pointed bubble, a horizontal cusp, or a horizontal flatness. [ABSTRACT FROM AUTHOR]

The paper studies the equilibrium configurations of inextensible elastic membranes exhibiting lateral fluidity. Using a continuum description of the membrane's motions based on the surface Navier–Stokes equations with bending forces, the paper derives differential equations governing the mechanical equilibrium. The equilibrium conditions are found to be independent of lateral viscosity and relate tension, pressure, and tangential velocity of the fluid. These conditions suggest that either the lateral fluid motion ceases or non-decaying stationary flow of mass can only be supported by surfaces with Killing vector fields, such as axisymmetric shapes. A shape equation is derived that extends the classical Helfrich model with an area constraint to membranes of non-negligible mass. Furthermore, the paper suggests a simple numerical method to compute solutions of the shape equation. Numerical experiments conducted reveal a diverse family of equilibrium configurations. The stability of equilibrium states involving lateral flow of mass remains an unresolved question. [ABSTRACT FROM AUTHOR]

In this paper, we consider the Cauchy problem of the 3D incompressible Keller–Segel–Navier–Stokes equations with partial diffusion, namely we remove the diffusion $ \Delta \rho $ Δ ρ. Using the damping effect of the growth term $ -\rho ^{3} $ − ρ 3 and the geometry of axisymmetric flow without swirl, we prove the global existence of weak solutions for the system. [ABSTRACT FROM AUTHOR]

Addressing the issue of leakage in practical scenarios involving hose pumps, this paper conducts an analysis on hose pumps with existing compression gaps. The model is simplified to represent the two-dimensional Newtonian fluid pulsating flow of a single-sided sine wave passing through the tube. The study derives the axial flow velocity distribution within the tube while establishing correlations between the leakage volume, tube clearance, pressure differential, deformed cross-sectional length of the tube, rotor speed (which exhibits a negative correlation), the deformation length of the tube in the x-direction, and the fluid's dynamic viscosity (demonstrating a positive correlation). Utilizing a bidirectional fluid-structure coupling method, this analysis investigates hose pumps with compression gaps. Specifically, it examines the flow field pressure, velocity, and vortex intensity of two Newtonian fluids with Reynolds numbers of 10–30 and 6000–15 000, respectively, within a 180° bend tube with a curvature-to-inner-diameter ratio of 4.6. This analysis is conducted under inlet velocities of 0.32 and 0.6 m/s, and outlet pressures of 0 and 0.1 MPa. The study identifies the positions of extreme leakage rates, elucidating the flow field characteristics and their impact on leakage. Furthermore, it investigates the causes of secondary flows within the tube, concluding that the fluid inside the tube exhibits symmetric helical motion. This research establishes the periodic variations in flow field vortex intensity and secondary flow intensity, along with the conclusion that leakage rates are positively correlated with axial vortex intensity and negatively correlated with secondary flow intensity. [ABSTRACT FROM AUTHOR]

This paper revisits the linear stability analysis of oscillatory-driven flows between two oscillating cylinders against non-axisymmetric disturbances. This study is motivated by the lack of a sufficiently reliable theoretical analysis giving insight into the experimentally observed spiral-like non-axisymmetric patterns when the cylinders are counter-oscillating. A new generalized time-dependent algebraic eigenvalue problem is constructed from the linearized set of the three-dimensional Navier–Stokes equations around the purely azimuthal basic state. Numerical evaluation of the critical eigenvalues combining both Floquet theory and spectral method reveals the existence of frequency ranges where this basic state becomes unstable against three-dimensional non-axisymmetric disturbances before it does so for two-dimensional axisymmetric ones. Indeed, as the oscillation frequency of the cylinders increases, the azimuthal wave number of the critical eigensolution is found to change from 0 to 2 to 1 and then back to 0. The primary bifurcation exchange between two instability modes with different azimuthal wave numbers occurs via different types of codimension-2 bifurcation points giving rise to discontinuities in the critical axial wave number where reversing and non-reversing non-axisymmetric Taylor vortex flows are identified. In addition, by extending our numerical calculations to the co-oscillating case, we show that the axisymmetric disturbances are the most unstable confirming thus existing experimental findings. Furthermore, a Wentzel–Kramers–Brillouin (WKB) analysis is performed to shed light on the asymptotic behavior of these time-dependent flows in the low-frequency limit when the cylinders are slowly oscillating. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation of the flow pattern regime and unsteady characteristics of ventilated cavities with different headform shapes. The test model consists of a removable headform with three different forebodies (the conical, the blunt, and the hemispherical) and a common cylinder rear body. Experiments are conducted in a closed-loop cavitation tunnel. First, the flow pattern regimes on the ventilated cavity for different headforms are discussed in detail, and the dimensions of several flow patterns are measured. The results show that the cavity dimension and the regime are strongly dependent on the headform shape, and all typical flow patterns are introduced by schematic illustrations. Second, the ventilation hysteresis that happened during the flow pattern transition is pointed out. A quantitative gas leakage model is employed to explain the cause of hysteresis and flow pattern transition, and the results show the Strouhal number for different headforms is approximately ∼0.21. However, the blunt presented stronger gas leakage with a large constant parameter, K = 0.80. Finally, the unsteady characteristics of the ventilated cavity around different tested headforms are involved through descriptions of developments of the recirculating vortex and transparent cavity. In addition, an estimated cavitation number is applied to investigate the unsteady characteristics, and the maximum cavitation number and the strongest characteristic are obtained by the blunt headform due to the large drag coefficient and strong flow separation. [ABSTRACT FROM AUTHOR]

Tip clearance is the distance required between the blade tip and the pump body wall of an impeller in a helicon-axial multiphase pump, which tends to induce tip leakage flow. The tip leakage vortex formed by the interaction of tip leakage flow with the mainstream can seriously affect the performance of the multiphase pump. To minimize the adverse effects of tip leakage flow in the multiphase pump, a method to design a squealer tip on the impeller blade is proposed in this paper. The effect of the squealer tip on external characteristics, tip clearance flow characteristics, and energy dissipation of the multiphase pump is analyzed. Research results indicate that the blade squealer tip can effectively improve hydraulic efficiency of the multiphase pump. At the optimal efficiency point, the head and hydraulic efficiency of the multiphase pump with a squealer tip increased by 3.62% and 4.15%, respectively, compared with the original model. The influence of tip leakage flow in the axial rear half passage of the multiphase pump impeller is far greater than that in the axial forward half passage, especially on the back position in the middle of the impeller passage. The squealer tip can restrain the reverse of leakage flow from the pressure side to the suction side of the impeller blade, and the clearance leakage flow of the model with a squealer tip is smaller than that of the original model. The squealer tip on blade will reduce the energy dissipation caused by unsteady flow in the mainstream. The research results in this paper can provide theoretical support for effectively restraining the influence of the tip leakage vortex on the mainstream of the helicon-axial multiphase pump and contribute to engineering practice value of improving the performance of the multiphase pump. [ABSTRACT FROM AUTHOR]

As a core component of a fan, the blade has a decisive impact on the aerodynamic performance of a low-pressure axial flow fan. Due to the limitations of the classical fan design theory on considering the complex 3D internal flow, the spanwise distribution of blade stacking line and section profiles are usually hard to reach the best state. This paper builds a surrogate-assistant multi-objective optimization flow combined with CFD method to explore the optimum blade shape under two typical working conditions. A total of 16 parameters were selected for demonstrating the blade stacking line and section profiles, according to Morris one-at-a-time sensitivity analysis. The objective and constraint functions were the fan's total-to-static efficiency and static pressure rise, respectively. During the optimization, the surrogate models of all response functions were built using kriging models, on which the multi-objective genetic algorithm takes the exploration. The optimization results indicate that the maximum improvement of the efficiency is 1.26 % for low mass flow working condition and 5.47 % for high mass flow working condition. The optimized models tend to make the low-pressure zone distributed along the blade leading edge in the meridian view and to reduce the tip leakage vortex intensity. This paper provides a good practical demonstration of multi-objective fine optimization on the blade shape of a low-pressure axial flow fan. [ABSTRACT FROM AUTHOR]

Heat transport in rotating processes finds a wide range of application in which academic issues in the fluid mechanics and heat transfer areas are here reported. This paper discusses successive works from the seminal paper of Taylor (1923) to recent numerical results established from a broad range of methods such as DNS, LES, RANS or LB methods. The flow regimes identification is thus reported in Taylor–Couette geometry. The role of the axial flow rates in the apparition, stabilization and destruction of the large-scale of the turbulent structures is depicted in the case of Taylor–Couette–Poiseuille geometry. In a non-isothermal condition, a discussion is held on the various exponent values found in the scaling relationships relying on the Nusselt number as a function of the Rayleigh or Reynolds numbers according to the regimes of thermal convection. [ABSTRACT FROM AUTHOR]

The present paper experimentally verified and computationally explained an improved design concept of the spray combustion of a gas–liquid pintle injector with variable swirl intensities. By pintle injector, we mean a promising injector for the throttleable engines with variable thrust capacities, which features the moveable pintle continuously controlling the mass flow rates of fuel and oxidizer where the radial and axial flows encounter to form a spray cone and spray atomization. First, the cold flow test was conducted to study the swirl effects on the spray angle, followed by the combustion test to study the total pressure and the specific impulse under different swirl intensities. The results show that the swirl enhances the combustion performance by increasing the total pressure and specific impulse. Second, the swirl-assisted spray was numerically simulated based on a validated volume-of-fluid method to explain the experimental findings. The diameter distribution and spatial distribution of dispersed droplets were analyzed by the Sauter mean diameter (SMD) and the Voronoi tessellation, respectively. The results show that the swirl significantly promotes the breakup of liquid jet or film, producing smaller SMDs and a more uniform spatial distribution of dispersed droplets. The consolidated correlation between the non-reacting spray characteristics and the combustion performance suggests that the proposed methodology can be used to fast prescreen pintle injector designs. [ABSTRACT FROM AUTHOR]

The paper is concerned with water vapor condensation on vertical pipes. The vertical position of pipes in a condenser is not discussed very often. Its application has a number of particularities in terms of the numerical determination of heat transfer. In the first stage of this paper, the authors focus on the experimental identification of heat transfer during vapor condensation on vertical pipes with a diameter of 14.0 × 1.0 mm. The pipes are placed in a narrow channel and the steam flows around them in a perpendicular direction. Two channel widths were tested, i.e., 20.0 and 24.0 mm. In the second stage, numerical modelling (CFD) is used for a detailed identification of the vapor velocity fields near the pipes. In the third stage, the results of the experimental measurements and numerical modelling are compared with data published by various authors. There are studies in the literature dealing with axial flow around vertical pipes; however, the associated results are based on conditions which are distinct from those applied in our study. The outcome of this paper is the specification of the heat transfer coefficient and the calculation formulas precisely describing the studied condenser configuration. [ABSTRACT FROM AUTHOR]

Turbulent swirl flow, which exists in numerous turbomachinery systems, is the focus of this paper. It consumes a significant amount of energy, so it is a subject of investigation for many researchers. It is even more present in ventilation systems, as numerous axial fans are still installed without guide vanes. The experimental investigation of the turbulent swirl flow behind an axial fan in a pipe, installed in a test rig with a free inlet and ducted outlet, as defined in the international standard ISO 5801, is presented in this paper. Moreover, in this paper, the axially restricted case is studied. A designed axial fan generates a Rankine vortex with a complex structure, and research on the vortex turbulence structure and dynamics is presented. On the basis of the HSS PIV (high-speed stereo particle image velocimetry), measurement results are calculated using invariant maps. All states of turbulence anisotropy are thoroughly analyzed by applying the invariant theory on HSS PIV results. Vortex dynamics is observed on the basis of the total velocity minima positions and their repetitions. Both methods are correlated, and important conclusions regarding vortex behavior are deduced. [ABSTRACT FROM AUTHOR]

In this paper, a closed-form frequency equation of the pipe-in-pipe (PIP) structure with arbitrary boundaries is obtained. The frequency equation is derived from Green's function of the transverse forced vibration of the PIP structure and takes into account the effects of internal two-phase flow and axial pressure. The reliability of the method in this paper is proved by comparison with the published literature. In the numerical discussion part, the PIP structures with clamped-clamped, clamped-free, and elastic boundary conditions are used as examples to discuss. The effects of equivalent stiffness coefficient, internal flow velocity, and gas volume fraction on the stability of PIP structure are studied. The results show that the stability of the PIP structure is better than that of the single-pipe structure, and the greater the equivalent stiffness coefficient of the elastic layer, the higher the critical flow velocity of the structure. In addition, a modal conversion phenomenon existing in the PIP structure is discovered. There are different forms of modal conversion for different boundary conditions, and the modal conversion makes the order of instability of the PIP structure different from that of a single-pipe. The conclusion of this paper has positive significance for the dynamic research of PIP structure. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies connected with the features of coolant hydrodynamics at the outlet of various design heads of a RITM fuel cassette for a nuclear icebreaker and an SNPP. Experiments were carried out using a research bench with an air working medium on a model of the fuel cassette outlet section by pneumometric and contrast injection methods based on the theory of hydrodynamic similarity. The hydrodynamic pattern of the coolant flow is visualized using cartograms of the axial velocity at the outlet of the fuel rod bundle, behind the FA heads of various designs, in front of the letdown pipe, as well as in the upper support plate. The determination of fuel rod bundle areas, where the coolant can flow into the letdown pipe, was carried out by the contrast injection method. The results of the studies establish the influence of the FA head design on the heterogeneity of the axial flow at the outlet of the fuel rod bundle and in front of the upper support plate. The more intensive mixing of the coolant behind the head of the fuel cassette of a nuclear icebreaker as compared to the head of the SNPP fuel cassette is due to the inhomogeneity of the flow leaving the passage holes of the heads. [ABSTRACT FROM AUTHOR]

The immersed boundary method (IBM) is currently utilized in the simulation of two-dimensional axisymmetric flow in solid rocket motors. In this paper, the IBM is applied to three-dimensional flow fields, keeping the grain surface fixed. Based on the Cartesian grid, a three-dimensional Euler flow solver is developed using the finite difference method. All boundaries of the flow field are processed using the IBM, including the slip walls, mass flow inlet, pressure outlet, and rotational periodic boundary. Specific implementation of these boundary conditions and the mesh generation process are described. Using the ray-casting approach and the alternating digital tree data structure, an efficient method is proposed to determine the intersection relationship between a rectangular volume grid cell and a triangular surface mesh element. The numerical results of Taylor–Culick flow verify that the developed solver has more than one-order accuracy in space. To conduct the validation of the established method, three typical grains are selected for flow simulations, namely, the perforated cylindrical grain with burning on both the ends and the inner surface, the end-slotted end-burning grain, and the finocyl grain, respectively. The simulated results are compared with those of the zero-dimensional interior ballistics, the two-dimensional axisymmetric IBM, and the body-fitted grid method, verifying the fidelity of the developed three-dimensional flow solver. [ABSTRACT FROM AUTHOR]

Over the last two decades, the tidal energy industry has laid the groundwork for creating commercially viable tidal power generation projects to strengthen sustainable energy policies around the world. At the end of 2021, the cumulative installation of tidal stream technology that has been deployed in Europe reached 30.2 MW, where the majority of the installations are by small and medium-sized companies. Due to a growing demand among investors related to the global tidal energy industry, the reliability and safety of operational-stage tidal energy systems' components are becoming increasingly important. In this context, companies, universities and research institutes are focusing on conducting large- and small-scale tests of tidal turbine elements to validate their projected design life, and major attention is being given to assessing the structural integrity of turbine blades. This review paper focuses on structural tests that have been reported for axial flow tidal turbine blades manufactured using composite materials around the world, highlighting the testing standards, equipment and instrumentation required. Overall, this review article discusses the state of the art in the structural testing of tidal turbine blades. In addition, it highlights the global concerns and research gaps to ensure the long-term sustainability of axial flow tidal turbine blades. In addition, the information contained in this article will be useful for formulating a smooth and reliable mechanism to enhance the evaluation process of the structural properties of tidal turbine blades in the future. [ABSTRACT FROM AUTHOR]

A Cartesian representation of the Taylor–Couette system in the vanishing limit of the gap between coaxial cylinders is presented, where the ratio, μ , of the angular velocities, ωi and ωo , of the inner and the outer cylinders, respectively, affects its axisymmetric flow structures. Our numerical stability study finds remarkable agreement with previous studies for the critical Taylor number, Tc(μ) , for the onset of axisymmetric instability. The Taylor number T can be expressed as T=Ω(R−Ω) , where Ω (the rotation number) and R (the Reynolds number) in the Cartesian system are related to the average and the difference of ωi and ωo. The instability sets in the region (Ω,R)→(0,∞) , while the product of Ω and R is kept finite. Furthermore, we developed a numerical code to calculate nonlinear axisymmetric flows. It is found that the mean flow distortion of the axisymmetric flow is antisymmetric across the gap when μ=1 , while a symmetric part of the mean flow distortion appears additionally when μ≠1. Our analysis also shows that for a finite R all flows with μ≠ 1 approach the R axis, so that the plane Couette flow system is recovered in the vanishing gap limit. This article is part of the theme issue 'Taylor–Couette and related flows on the centennial of Taylor's seminal Philosophical Transactions paper (part 2)'. [ABSTRACT FROM AUTHOR]

The presence of structures in the ocean complicates the navigation of an underwater axisymmetric body. This effect involves special environmental fluid dynamics, such as unsteadiness, strong nonlinearity, cavity multiphase flow, strong turbulence, and so forth. In this paper, an improved delayed detached eddy simulation method is used to investigate the ventilated cavity flow of an axisymmetric body in the ocean, with the intent of exploring differences in cavity multiphase flow characteristics in the presence and absence of a structure. The presence of the structure advances the deflation of the tail, shortening the length of the main body of the ventilated cavity by 21.1%. In addition, the interference of the structure increases the shedding of multi-scale vortices, while the cavity body and the shedding vortices appear asymmetrical. Moreover, the existence of the structure increases the violence of the pressure fluctuation of the axisymmetric body, where the pressure fluctuation directly below the structure reaches 57.6%, and the fluctuation of the distribution probability of the cavitation number also increases. It is worth noting that the existence of the structure does not change the main frequency of the ventilated cavity shedding in front of the structure. [ABSTRACT FROM AUTHOR]

• Decay of swirling flow and heat transfer parameters in a long straight pipe (l/d = 150) is experimentally studied. • Eight blade-type swirl generators with central body are tested. • Flow and heat transfer parameters are summarised and correlated using the swirl flow number. • Conclusions are made regarding transition from swirling to axial flow in terms of the energy loss reduction and heat transfer decay. • Heat transfer demonstrates the earliest transition to axial flow conditions. This paper describes an experimental study of heat transfer, local and total swirl flow parameters in the pipe 80 mm in a diameter and 150 diameters long. The pipe consists of 12 separate pipes of different length, connected to each other using 20 mm ring spacers. These spacers were also used to provide the flow and heat transfer measurements. Overall, eight blade-type swirl generators with central body and profiled according to the power low, are installed at the pipe inlet. The actual swirl intensity S of swirl generators is ranged from 0.38 to 1.29. The profiles of mean axial and tangential velocity, surface heat flux, swirl flow angle, static and total pressure, flow and surface temperature are measured. A few novel scientific results and equations are obtained, including the axial and tangential speed maximum, axial and tangential momentum flux, swirl number decay and energy loss transformation. The common link between the local and total swirl parameters, one-valued correlation between tangential and axial velocity were obtained. The results, presented in the paper led to the conclusion that transition from swirling to axial flow occurs at S ≈ 0.19 in terms of the heat transfer decrease, but at S ≈ 0.10 – in terms of the energy loss reduction. [ABSTRACT FROM AUTHOR]

Elastic ring squeeze film damper (ERSFD) is extensively used in industrial rotating systems due to its excellent noise control and vibration suppression characteristics. However, the oil film sealing and leakage has a profound effect on the mechanical and vibration characteristics of the ERSFD and the ERSFD-rotor during operation. The sealing and leakage reduce the axial flow of the oil film, leading to changes in the initial boundary conditions of the flow field, which in turn affects the oil film pressure and damping coefficient of ERSFD. Meanwhile, the sealing causes an increase in the oil film force of ERSFD, which in turn affects the response of the rotor system. But there is relatively little research on the impact of sealing and leakage on the dynamic performances of ERSFD-rotor. In this paper, a mathematical model of ERSFD under different sealing conditions (no end seal, complete end seal, piston ring seal, O-ring seal) is established by changing the initial boundary equations of the flow field of ERSFD and the coupled solution of the Reynolds equation of ERSFD with different sealing and leakage boundary equations is realized. Then, the characteristics of oil film pressure and force of ERSFD under different sealing conditions is studied. After that, an ERSFD-rotor model considering oil film sealing and leakage is established based on displacement compatibility conditions and force balance principles. Meanwhile, the impact of sealing and leakage on the amplitude-frequency relation and sudden imbalance of an ERSFD combined support rotor is researched. The research results reveal that good sealing can significantly increase the damping of the system, thereby reducing the vibration amplitude of the ERSFD-rotor system. In addition, good sealing conditions can also shorten the transient process of sudden unbalanced excitation. Finally, the effectiveness of some simulation results was verified through experiments on the ERSFD rotor test bench. • This paper proposes a model of ERSFD under different sealing conditions by coupling different boundary equations. • The dynamic characteristics of oil film pressure and force of ERSFD under different sealing conditions are analyzed. • The impact of different sealing and leakage conditions on vibration amplitude and damping of ERSFD rotor is analyzed. • Experimental testing for the amplitude frequency response of ERSFD-rotor with no end seal is carried out. [ABSTRACT FROM AUTHOR]

• The present paper evaluates thermochemical effects on Orion at the beginning of an entry path. • Effects of chemical reactions and of typology of entry trajectory (direct and orbit) are evaluated. • Heat flux associated to the surface recombination reactions is also estimated. It is well known that NASA developed the Orion project, besides for a rescue shuttle for the International Space Station, also for the transportation of instruments and astronauts to Moon, Mars and beyond. The forthcoming use of Orion for Mars landing stimulated Zuppardi to compute global aerodynamic coefficients in rarefied, transitional flow along a high altitude entry path. A Direct Simulation Monte Carlo (DSMC) code computed the coefficients at the altitudes of 80, 90 and 100 km, in the range of angles of attack 0–180 deg. The aim of the present paper, that can be considered as the logic follow on of the previous paper by Zuppardi, is to evaluate, in high altitude entry path, the influence of: 1) chemical reactions on the flow field and on some local quantities (temperature, pressure and heat flux) along the Orion surface, 2) typology of entry trajectory (direct and orbit) on both local quantities and drag coefficient, 3) heat flux associated to the surface recombination reactions. Computations were carried out in axisymmetric flow and in the altitudes interval 60–100 km by means of a home made code for the computation of the entry trajectories and of the powerful and advanced two-dimentional/axisymmetric DSMC code (DS2V) for the solution of the flow field around Orion. [ABSTRACT FROM AUTHOR]

Notwithstanding the long historic journey of Kaplan turbines for hydropower generation, the inner design details like position of guide vane relative to runner, blade pitch to chord ratio amongst others are yet to be investigated in depth let alone being standardized. This dearth widens in small capacity hydropower plants. The current study chooses the blade pitch to chord as research theme to be investigated both experimentally and numerically on a medium-high specific speed Kaplan turbine. Three levels of study are envisaged for obtaining the optimum ratio. The first is the change of blade number with chord fixed, the second is fixing the blade number and changing the chord length and final level of keeping the ratio constant by varying the pitch and chord by identical proportion attempts to clarify the scaling effects. Optimum efficiency in the range of 78%–82% for ratios 1.2 to 2.2 are observed for smaller pitch, smaller chord condition. The scaling study at optimum ratio revealed that increasing the blade pitch distance causes the exit fluid deflection deteriorating the performance. The paper strongly recommends a wider pitch-chord ratio study in higher specific speed Kaplans to get standardized scaling effects with respect to size and achieve universality. • Kaplan turbine with 4 blades,D = 218 mm,1570 rpm,pitch(t)/chord(t) at tip = 1.6 chosen. • 9 cases investigated with blade number 2, 3 and 4; chord length ratio 0.5, 0.75, 1.0 • Efficiency increased by 15% as t/l decreased from 3.2 to 1.6, at fixed chord 'l'. • Small pitch and small chords improved performance by 2–8% at given t/l. • Novel study of scaling effect done on inter-blade space and fluid deflection. [ABSTRACT FROM AUTHOR]

In this paper, we prove the uniqueness and structural stability of Poiseuille flows for axisymmetric solutions of steady Navier–Stokes system supplemented with Navier boundary conditions in a periodic pipe. Moreover, the stability is uniform with respect to both the flux and the slip coefficient of Navier boundary conditions. It is also shown that the nonzero frequency part of the velocity is bounded by a power function of the flux with negative power as long as the flux is suitably large. One of the key ingredients of the analysis is to prove the uniform linear structural stability, where the detailed analysis for the boundary layers and the swirl velocity corresponding to the flux and the slip coefficients in different regimes plays a crucial role. [ABSTRACT FROM AUTHOR]

The aerodynamic shape of the hypersonic forebody/inlet integrated vehicle is usually designed according to the inviscid flow. However, due to the effect of air viscosity, there is a boundary layer flow near the wall surface. In order to get the actual flow characteristics and performance parameters of the inviscid design vehicle close to the inviscid design values, the inviscid design surface must be corrected by considering the viscous boundary layer. In this paper, the theory and method of the boundary-layer viscous correction (BLVC) for the forebody/inlet integrated configuration are studied. Firstly, two modification schemes of the BLVC for the forebody/inlet integrated configuration are proposed. The calculation method of boundary-layer displacement thickness (BLDT) based on the momentum integral equation of steady two-dimensional (2D) axisymmetric compressible flow is described in detail, and two calculation methods of the BLDT are compared and analyzed. Secondly, the numerical simulation method used in this paper and its validation are introduced. Thirdly, an axisymmetric configuration of the forebody/inlet integration is selected as the first case, and two modification schemes of BLVC are studied and analyzed by numerical simulation. The effects of the two modification schemes of BLVC on the internal and external flow characteristics and aerodynamic performance of the axisymmetric configuration of the forebody/inlet integration are compared and analyzed. Finally, a full-waverider configuration of the forebody/inlet integration is selected as the second case, and the second modification scheme of the BLVC is used to modify the full-waverider configuration. The shock wave characteristics and inlet performance parameters of the modified full-waverider configuration are studied by both the numerical simulation and the wind tunnel experiment. The obtained results prove that the calculation method of the BLDT by a numerical integration method to solve the momentum integral equation of the steady 2D axisymmetric compressible flow is correct and the BLVC method and scheme for the forebody/inlet integrated configuration are effective. The modification scheme 1 of the BLVC can only improve the characteristics of forebody shock wave incident on the inlet lip under viscous conditions, that is, to improve the performance of inlet to capture precompressed air flow, while the modification scheme 2 of the BLVC can simultaneously improve the characteristics of forebody shock wave incident on the inlet lip and the characteristics of the lip shock wave cancelled on the shoulder of the inlet under viscous conditions, and make the air flow capture performance of the inlet and the pressure rise ratio at the inlet exit close to those of the inviscid design state. • Boundary-layer viscous correction for forebody/inlet integration is proposed. • Two modification schemes of boundary-layer viscous correction are analyzed. • Both numerical simulation and wind tunnel experiment are applied to this study. • Inviscid design forebody/inlet integrated vehicle are correctly effectively. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) axisymmetric simulation is an efficient and time-saving computational fluid dynamics (CFD) technique when the body is axisymmetric, and the flow is along the length of the body. In the present paper, this technique is used to investigate turbulent flow around the bare hull configuration of the Defense Advanced Research Project Agency submarine model. Verification and validation of the results are done at three levels. The values of the total resistance, the distribution of the wall shear stress and the pressure on the surface, and the velocity profiles at various distances from the nose are compared with results obtained by using three-dimensional (3D) simulations and experimental results from the literature. The uncertainty in CFD results due to meshing is reported using Richardson Extrapolation. It is shown that the errors are minor, and the savings in computer memory and computation time are tremendous using 2D axisymmetric simulations. Good CFD practices essential for 2D axisymmetric simulations are also presented in this article, which will be helpful for the CFD community to conduct numerical investigations on any other axisymmetric bare hull bodies, such as torpedoes, missiles, submarines, and autonomous underwater vehicles in the future. Finally, the components of drag, coefficient of pressure, and wall shear stress at the highest speed (9.26 m/s) are also obtained using 2D axisymmetric simulation, which has not been previously reported in any other literature. The level of rigor in the 2D axisymmetric simulation reported here is rarely seen in recent literature. [ABSTRACT FROM AUTHOR]