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In this paper, a high-order hybrid method for solving compressible two-phase fluid flow, including cavitation, is presented. In this regard, assuming pressure and temperature equilibrium, mass and heat transfer between the different phases are modeled. In this work, the CRMWENOZ method, which is a new combination of compact and weighted essentially non-oscillatory (WENO) methods and is more accurate than conventional methods, is presented. The new high-order hybrid method aims to predict the density and the pressure discontinuities in two-phase flow by combining the CRMWENOZ high-order method and an adaptive moving mesh technique. For this purpose, the adaptive moving mesh partial differential equation (MMPDE) method would also improve the accuracy of results by concentrating on the grid nodes in high-gradient regions for transient flows. Applying the CRMWENOZ method alongside MMPDE and using the fifth-order Radau method for time discretization lead to a substantial improvement in the accuracy of simulation, particularly near the liquid–gas interfaces. The accuracy of the proposed hybrid method was compared to other studies' predictions of one-dimensional (1D) expansion and shock tube problems containing two-phase flow with and without cavitation. The results showed that the hybrid method presented was more accurate than the usual two-phase flow methods while using a reasonable amount of computer resources. [ABSTRACT FROM AUTHOR]

The integrated bubbly wake strength of two ship models with different scales is investigated in this paper. The laser spot video recording technique is implemented to measure the light scattering properties of laser beams transmitted through the wake. The bubbly wake is generated by the movement of two geometrically similar models towed at constant velocities in a towing tank. The effect of the model's velocity and scale are investigated using data provided by the multiple laser emitter and detectors. Results show the dominance of small bubbles on the persistence of the wake. Also, the effects of wetness of the stern on the vertical distribution of the wake are evident. Comparing the wake of two scale models shows a stronger wake for the bigger model in similar conditions. Moreover, the importance of Froude and Weber numbers on the scaling of major features of the bubbly wake of ship models is prominent. [ABSTRACT FROM AUTHOR]

In this paper a new bubbly flow measurement procedure is proposed which can be used to both detect and quantify some main features of such flows. The proposed procedure is based on the optical scattering behavior of a laser-beam passing through a bubbly flow. A series of experiments are conducted to evaluate the procedure and important parameters involved such as length of bubbly flow, bubble number density and size distribution. Experimental results confirm the capabilities of the procedure for the detection and quantification of bubbly flows. Also, an optical model of the laser beam behavior in bubbly flow is derived to reevaluate the problem and its results are compared with the obtained experimental results. Outcomes of the optical model, which is in good agreement with the experimental results, emphasizes and describes the strong correlation between the injection strength parameter and forward scattered light intensity. Also, bubble size distribution is found to be in close connection with the amplitude of scattered light fluctuations. Therefore, upon the measurement of optical laser-beam scattering behavior passing through a bubbly flow, various properties of such flows could be determined. [ABSTRACT FROM AUTHOR]

An analysis of flow was carried out in this study to find the effects of trees on the flow structure in a straight compound open channel. To resemble the vegetation stem, two rows of vertical rods were installed on the floodplain of an asymmetrical compound channel. Two-dimensional flow velocity was measured using Particle Image Velocimetry. The results showed a decreasing trend in turbulent kinetic energy and turbulent intensity along the floodplain. At low flow depth, a significant decrease was observed in mean velocity and kinetic energy. Similar reduction was observed at the intersection of floodplain and main channel and around the stems. Under this condition, the direction of velocity vectors changed from floodplain to the main channel. However, this trend was reversed at higher flow depths. This reversal was due to the changes in momentum transfer and shear stress at the intersection of floodplain and main channel. Additionally, a numerical analysis showed that vortices are formed at the junction of the floodplain and main channel. [ABSTRACT FROM AUTHOR]

In the present contribution attention is focused to extend the application of multifluid descriptions to rarefied conditions for the first time. To this aim, a multifluid Maxwell model and a multifluid Smoluchowski model are proposed for near wall behavior of the constituents of a rarefied gas mixture. Afterwards, multifluid balance equations in conjunction with these boundary conditions are solved for some slip flows of binary gas mixtures between parallel plates. The corresponding results are compared with those of a previously developed Navier-Stokes solver. Inspection of the results indicates that while the Navier-Stokes equations may lose their accuracy under high rarefaction, non-equilibrium features are properly captured by developed multifluid description. This successful method is thereafter utilized to discuss the consequences of velocity-slip, the tangential-momentum-accommodation coefficient, and mass disparity of the mixture constituents on the degree of non-equilibrium between the constituents of the gas mixtures between parallel plates. [ABSTRACT FROM AUTHOR]

One of the most promising methods for cancer treatment that is developed substantially in theoretical and clinical fields is hyperthermia. Magnetic hyperthermia using nanoparticles has significant advantages in comparison with other hyperthermia treatments. Providing the proper dosage of magnetic nanoparticles (MNPs) in the proper location(s) is one the most challenging steps of this procedure. In the present article, an efficient and robust analytical algorithm to determine the proper injection location(s) and dosage(s) in addition to the number of infusions for an arbitrary cancerous cells distribution in the tissue is presented. The method is based on temperature elevation of tumor spots to a specified amount and prevention of overheating in the nearby healthy tissues. The algorithm is based on tissue imaging, hyperthermia level decision, and implementation of inverse Fourier's transformation, Green's function, as well as genetic algorithm. Based on the obtained results, the algorithm can achieve 17% and 12% relative deviation error with respect to the desired temperature for uniform and concentrated cancerous cells distribution pattern, respectively, while for the more complex pattern examined, the error increased to 25%, which is quite promising for the complex test case. [ABSTRACT FROM AUTHOR]

In this study, a numerical investigation is performed to evaluate the effects of high-pressure sinusoidal and blast wave's propagation around and inside of a human external ear. A series of computed tomography images are used to reconstruct a realistic three-dimensional (3D) model of a human ear canal and the auricle. The airflow field is then computed by solving the governing differential equations in the time domain using a computational fluid dynamics software. An unsteady algorithm is used to obtain the high-pressure wave propagation throughout the ear canal which is validated against the available analytical and numerical data in literature. The effects of frequency, wave shape, and the auricle on pressure distribution are then evaluated and discussed. The results clearly indicate that the frequency plays a key role on pressure distribution within the ear canal. At 4 kHz frequency, the pressure magnitude is much more amplified within the ear canal than the frequencies of 2 and 6 kHz, for the incident wave angle of 90° investigated in this study, attributable to the ‘4-kHz notch’ in patients with noise-induced hearing loss. According to the results, the pressure distribution patterns at the ear canal are very similar for both sinusoidal pressure waveform with the frequency of 2 kHz and blast wave. The ratio of the peak pressure value at the eardrum to that at the canal entrance increases from about 8% to 30% as the peak pressure value of the blast wave increases from 5 to 100 kPa for the incident wave angle of 90° investigated in this study. Furthermore, incorporation of the auricle to the ear canal model is associated with centerline pressure magnitudes of about 50% and 7% more than those of the ear canal model without the auricle throughout the ear canal for sinusoidal and blast waves, respectively, without any significant effect on pressure distribution pattern along the ear canal for the incident wave angle of 90° investigated in this study. [ABSTRACT FROM AUTHOR]

In the present study, six solitary wave generations by different mathematical approximations are investigated using a piston type wave maker at dimensionless amplitudes ranging from 0.1 to 0.6 and two water depths. Incompressible smoothed particle hydrodynamics is used to simulate solitary wave propagation along the fixed depth channel. The present numerical results are compared with analytical results and experimental data in terms of free surface displacements, fluid particle velocity, phase speed, paddle motion, etc. The present mesh-free numerical results of wave profile variations over time proved that “Rayleigh” has the lowest relative wave height variation. However, its solitary wave has notable phase lead, while “Third order” and “Ninth order” have the least wave lags. Furthermore, the record of present numerical free surface elevation at different distances and the loss of amplitude of the main pulse showed that regarding both of them, “Ninth order” has supremacy over five others. Considering the numerical velocity components of generated solitary wave, “Third order” and “Ninth order” trace analytical results more accurately than other four ones, whereas “Rayleigh” is the most accurate one in predicting the maximum runup. Finally, the paddle motion, its velocity, and displacement, as well as phase speed and outskirts decay coefficient are also compared and discussed intensely. [ABSTRACT FROM AUTHOR]