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In this paper, we consider 3D compressible magneto-micropolar fluids without resistivity and spin viscosity in a strip domain. The prominent character of the governing model is the presence of the microstructure, a linear coupling structure involving derivatives of the velocity fields, which along with the lack of spin viscosity brings several challenges to the analysis. By exploiting the two-tier energy method developed in Guo and Tice (Arch Ration Mech Anal, 2013), we prove the global existence of classical solutions to the governing model around a uniform magnetic field that is non-parallel to the horizontal boundary. Moreover, we show that the solution converges to the steady state at an almost exponential rate as time goes to infinity. One of the main ingredients in our analysis, compared with previous works on micropolar fluids, is that we deal with the microstructure by establishing some delicate estimates based on the analysis of the div-curl decomposition, and the coupling between the fluid velocity and the vorticity of angular velocity. [ABSTRACT FROM AUTHOR]

In this work, we prove the uniform regularity of smooth solutions to the full compressible magnetohydrodynamics (MHD) system with zero heat conductivity. [ABSTRACT FROM AUTHOR]

In this paper we study the compressible magnetohydrodynamics equations in three dimensions, which offer a good model for plasmas. Formation of singularity for C 1 -solution in finite time is proved with axisymmetric initial data. The key observation is that the magnetic force term admits a good structure with axisymmetric assumption. [ABSTRACT FROM AUTHOR]

This study highlights the potential utilization of hydrogen gas in electric arc furnaces for achieving cleaner and more sustainable steel production. The application of hydrogen offers a promising path for reducing carbon emissions, enhancing energy efficiency, and advancing the concept of "green steel". This study employs a 2D axisymmetric induction-based model to simulate an electric arc under atmospheric pressure conditions. We conducted numerical simulations to compare compressible and incompressible models of an electric arc. The impact of compressibility on hydrogen arc characteristics such as arc velocity, temperature distribution, and voltage drop were investigated. Additionally, different applied current arcs were simulated using the compressible model. When compared to an incompressible arc, the compressible arc exhibits a higher voltage drop. This higher voltage drop is associated with lower temperatures and lower arc velocity. A rise in applied current results in an upward trend in the voltage drop and an increase in the arc radius. In addition, the increased applied current increases the probability of voltage fluctuations. The voltage fluctuations tend to become more extreme and exert more stress on the control circuit. This has an impact on emerging electric arc technologies, particularly those involving the use of hydrogen. These fluctuations affect arc stability, heat output, and the overall quality of processes. Thus, the precise prediction of voltage and the ability to stabilize the operation is critical for the successful implementation of new hydrogen technologies. [ABSTRACT FROM AUTHOR]

The ventilation design of mines is based on fluid dynamics. Air is the main fluid in mining ventilation. This fluid is analyzed by two models: incompressibility and compressibility. The air-fluid in the compressibility model is examined in two models of dry and wet air along with thermal analysis. This paper argues that a number of presented parameters in the common thermodynamic analysis of mine ventilation should be modified. Accordingly, issues of the Earth's true gravity acceleration, potential energy difference, the specific heat capacity of air at constant pressure and volume, enthalpy difference of air, the average volumetric mass of dry air, and the amount of output moisture are rechecked. Therefore, a new method is presented in this paper for correcting thermodynamic equations in mine ventilation design. The name of this method is the Complete Model of Wet Air Analysis (CMWAA method). The results of this paper show that the CMWAA method can accurately perform thermodynamic analysis of air-fluid in mine ventilation without requiring a specified evaporation rate in mine networks, with minimal iteration of calculations.

There have been ample three-dimensional (3D) wearable piezoresistive sensors with high sensitivity, fast response, and outstanding long-term stability. Nevertheless, less consideration is given to simple fabrication, economical materials, and comfort. Herein, a simple and cost-effective strategy for fabricating piezoresistive sensors is presented based on commercial 3D air-laid nonwovens (NW), poly(tetrafluoroethylene-co-hexafluoropropylene-co-vinylidene fluoride) (THV), and carbon nanotubes (CNTs) via one-step dip-coating method. CNTs without functionalization are dispersed homogenously in the solvent and coated uniformly on the substrate with the help of THV as dispersant and adhesive. This highly compressible 3D NW-THV-CNTs piezoresistive sensor showcases splendent air permeability (2682.33 mm·s−1), water–vapor permeability (1625.50 g·m−2·d−1) and super-hydrophobicity (water contact angle = 158.5°), and is characterized by remarkable photothermal performance. Furthermore, the NW-THV-CNTs sensor has a sensitivity of 1.26 kPa−1 with good linearity (r2 = 0.99833) in wide detecting range (0–100 kPa), moderate response time (0.45 s) and release time (0.25 s), and good cyclic stability. Additionally, the sensor excels in monitoring human activities, and the array sensor composed of 4 × 4 pixels is capable of plotting distribution and shape of pressure. [ABSTRACT FROM AUTHOR]

The ventilation design of mines is based on fluid dynamics. Air is the main fluid in mining ventilation. This fluid is analyzed by two models: incompressibility and compressibility. The air-fluid in the compressibility model is examined in two models of dry and wet air along with thermal analysis. This paper argues that a number of presented parameters in the common thermodynamic analysis of mine ventilation should be modified. Accordingly, issues of the Earth's true gravity acceleration, potential energy difference, the specific heat capacity of air at constant pressure and volume, enthalpy difference of air, the average volumetric mass of dry air, and the amount of output moisture are rechecked. Therefore, a new method is presented in this paper for correcting thermodynamic equations in mine ventilation design. The name of this method is the Complete Model of Wet Air Analysis (CMWAA method). The results of this paper show that the CMWAA method can accurately perform thermodynamic analysis of air-fluid in mine ventilation without requiring a specified evaporation rate in mine networks, with minimal iteration of calculations. [ABSTRACT FROM AUTHOR]

Three-dimensional aerogels with ultralow density and extraordinary mechanical properties have attracted a lot of interest for their broad technological applications. Herein, lightweight, compressible, and multifunctional organic–inorganic nanofibrous aerogels are constructed by combining inorganic Fe7S8 doped honeycomb-like porous carbon nanofiber (Fe7S8/PCNF) and organic aramid nanofiber (ANF). The obtained Fe7S8/PCNF@ANF nanofibrous hybrid aerogels exhibit an interconnected lamellar structure, which endows the aerogels with an ultralow density of 0.014 g/cm3 and excellent compressibility of more than 95% compressive stress retention after 100 cycles at 40% strain. As an electromagnetic microwave absorber, the interconnected lamellar structure of aerogels, the homogeneously doped Fe7S8 nanosheets, and the honeycomb-like pores of carbon nanofiber enhance the impedance matching, enabling more microwaves to enter the aerogels to be dissipated. More importantly, the macroscopic lamellar network induces multiple reflecting and scattering to extend the transmitted pathways of microwaves, thus enhancing the attenuation ability of the absorber. When the mass-filling ratio of the materials to paraffin wax is 1:9, the obtained aerogels achieve a strong absorption of −37.0 dB at 15.7 GHz and a broad bandwidth of 5.52 GHz at a thickness of 2.0 mm. Meanwhile, the obtained aerogels present superior thermal insulation performance with thermal conductivity of 0.193 W/mK and outstanding hydrophobicity property with a water contact angle of 145°, guaranteeing the durable application of the absorber in extremely humid and high-temperature environments. This work may shed some light on designing new-generation microwave absorbing materials with multiple applications. [ABSTRACT FROM AUTHOR]

We study the impact of compressibility on two-dimensional turbulent flows, such as those modeling astrophysical disks. We demonstrate that the direction of cascade undergoes continuous transition as the Mach number Ma increases, from inverse at Ma = 0, to direct at M a = ∞. Thus, at M a ∼ 1 comparable amounts of energy flow from the pumping scale to large and small scales, in accord with previous data. For supersonic turbulence with M a ≫ 1 the cascade is direct, as in three dimensions, which results in multifractal density field. For that regime ( M a ≫ 1) we derive a Kolmogorov-type law for potential forcing and obtain an explicit expression for the third order correlation tensor of the velocity. We further show that all third order structure functions are zero up to first order in the inertial range scales, which is in sharp contrast with incompressible turbulence where the third order structure function, that describes the energy flux associated with the energy cascade is non-zero. The properties of compressible turbulence have significant implications on the amplification of magnetic fields in conducting fluids. We thus demonstrate that imposing external magnetic field on compressible flows of conducting fluids allows to manipulate the flow producing possibly large changes even at small Mach numbers. Thus Zeldovich's antidynamo theorem, by which at Ma = 0 the magnetic field is zero in the steady state, must be used with caution. Real flows have finite Ma and, however small it is, for large enough values of I, the magnetic flux through the disk, the magnetic field changes the flow appreciably, or rearranges it completely. This renders the limit Ma → 0 singular for non-zero values of I. Of particular interest is the effect of the density multifractality, at M a ≫ 1 which is relevant for astrophysical disks. We demonstrate that in that regime, in the presence of non-zero I the magnetic field energy is enhanced by a large factor as compared to its estimates based on the mean field. Finally, based on the insights described above, we propose a novel two-dimensional Burgers' turbulence, whose three-dimensional counterpart is used for studies of the large-scale structure of the Universe, as a model for supersonic two-dimensional magnetohydrodynamic flows. [ABSTRACT FROM AUTHOR]

We investigate global existence and optimal decay rates of a generic non-conservative compressible two–fluid model with general constant viscosities and capillary coefficients, and our main purpose is three–fold: First, for any integer ℓ ≥ 3 , we show that the densities and velocities converge to their corresponding equilibrium states at the L 2 rate (1 + t) - 3 4 , and the k( ∈ [ 1 , ℓ ] )–order spatial derivatives of them converge to zero at the L 2 rate (1 + t) - 3 4 - k 2 , which are the same as ones of the compressible Navier–Stokes–Korteweg system. This can be regarded as non-straightforward generalization from the compressible Navier–Stokes–Korteweg system to the two–fluid model. Compared to the compressible Navier–Stokes–Korteweg system, many new mathematical challenges occur since the corresponding model is non-conservative, and its nonlinear structure is very terrible, and the corresponding linear system cannot be diagonalizable. One of key observations here is that to tackle with the strongly coupling terms, we will introduce the linear combination of the fraction densities ( β + α + ρ + + β - α - ρ - ), and explore its good regularity, which is particularly better than ones of two fraction densities ( α ± ρ ± ) themselves. Second, the linear combination of the fraction densities ( β + α + ρ + + β - α - ρ - ) converges to its corresponding equilibrium state at the L 2 rate (1 + t) - 3 4 , and its k( ∈ [ 1 , ℓ ] )–order spatial derivative converges to zero at the L 2 rate (1 + t) - 3 4 - k 2 , but the fraction densities ( α ± ρ ± ) themselves converge to their corresponding equilibrium states at the L 2 rate (1 + t) - 1 4 , and the k( ∈ [ 1 , ℓ ] )–order spatial derivatives of them converge to zero at the L 2 rate (1 + t) - 1 4 - k 2 , which are slower than ones of their linear combination ( β + α + ρ + + β - α - ρ - ) and the densities. We think that this phenomenon should owe to the special structure of the system. Finally, for well–chosen initial data, we also prove the lower bounds on the decay rates, which are the same as those of the upper decay rates. Therefore, these decay rates are optimal for the compressible two–fluid model. [ABSTRACT FROM AUTHOR]

A new method is shown to provide a solution to the long standing pressure-velocity coupling problem encountered in pressure-based Computational Fluid Dynamics. This problem occurs when the dependent variables are colocated on the computational mesh. A solution was found by requiring that the interpolation equations, used to relate the velocity and density at the control volume faces to the nodal values, be constrained to conserve mass. This is referred to as Mass Constrained Interpolation. It also leads to a strategy for deriving and testing boundary conditions. The method is demonstrated by comparing one-dimensional computational solutions to exact solutions for a wide range of incompressible and compressible flows. [ABSTRACT FROM AUTHOR]

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This paper investigates the effect of initial conditions characterized by compressibility of turbulence on the changes in scalar such as density, temperature, and pressure within the framework of rapid distortion theory (RDT) in the case of non-isentropic turbulence. This study is a follow-up of the basic work carried out by A. Simone, G.N. Coleman and C. Cambon [J. Fluid Mech. 330, 307 (1997)] in the case of quasi-isentropic turbulence and the previous work of M. Riahi and T. Lili [Fluid Dyn. Res. 52, 025501 (2020)] in the case of non-isentropic turbulence. RDT was used to examine the behavior of the root mean square (rms) fluctuations of density, temperature, and pressure. The coupling between these rms quantities, the partition factor, and the polytropic coefficient was also studied. RDT equations were solved numerically using a code that solves directly evolution equations of two-point spectral correlations for compressible homogeneous sheared non-isentropic turbulence. The RDT analysis was carried out for various initial turbulent Mach numbers Mt0 ranging from 0.1 to 0.4, and the initial compressible turbulence is to be one of the three states concerning the fraction of kinetic energy χ0: solenoidal (χ0 = 0), mixed (χ0 = 0.6), and dilatational (χ0 = 1) (χ0 is the ratio of the initial dilatational kinetic energy to the initial total kinetic energy). It is shown from this study that the changes in scalars are strongly dependent on the initial conditions. Magnitudes and asymptotic values of rms thermodynamics fluctuations and correlations between these thermodynamics fluctuations depend of Mt0. For large times, the isentropic state of the flow is well observed whatever Mt0 and χ0. [ABSTRACT FROM AUTHOR]

The objective of this paper is to generalize an Ogden-type model for elastically isotropic response to include elastic-viscoplastic response. The proposed model uses a strain energy function that depends on the total dilatation and the maximum and minimum elastic distortional stretches. A novel feature of the model is that these elastic distortional stretches are expressed in terms of two independent invariants of an elastic distortional deformation tensor that is determined by an evolution equation. The Cauchy stress is determined by derivatives of the strain energy function, the dilatation and the elastic distortional deformation tensor without the need for determining its principal directions. Examples demonstrate the response of the model for hyperelastic response but the proposed formulation can also model a smooth elastic-plastic transition with rate-independent or rate-dependent response with hardening. [ABSTRACT FROM AUTHOR]

In this paper, we consider a diffuse interface model coupled by Navier–Stokes equations and Allen–Cahn equations. We study 1D compressible system with free boundary when the initial density is assumed to be compactly supported and connects to vacuum continuously. The global existence of weak solutions is established by using line method. [ABSTRACT FROM AUTHOR]

Ignition and relighting in supersonic flows is an important challenge for the design of hypersonic propulsion systems. Supersonic compressible flows of interest exhibit much larger local variations in velocity, shear, and thermodynamic state than their incompressible counterparts. Thus, it is of interest to study the relationship between ignition kernel evolution, the initial spark location, and the kernel's subsequent flow state history. We leverage the flexibility of a laser plasma ignition system to systematically explore a large set of spark locations on the symmetry plane of an ethylene jet in supersonic crossflow setup. CH* measurements are used to visualize chemically active regions and results are correlated with flow field properties derived from Mie-scattering data of the non-reacting flow field. Our study describes the laser plasma properties in detail and scrutinizes the effect of turbulent mixing and flow dilatation on ignition kernels. Finally, the results yield general guidelines for favorable ignition locations in the engineering design of chemically reactive compressible flows. [ABSTRACT FROM AUTHOR]

When simulating multiphase compressible flows using the diffuse‐interface methods, the test cases presented in the literature to validate the modellings with regard to interface problems are always textbook cases: interfaces are sharp and the simulations therefore easily converge to the exact solutions. In real problems, it is rather different because the waves encounter moving interfaces which consequently have already undergone the effects of numerical diffusion. Numerical solutions resulting from the interactions of waves with diffused interfaces have never been precisely investigated and for good reasons, the results obtained are extremely dependent on the model used. Precisely, well‐posed models present similar and important issues when such an interaction occurs, coming from the appearance of a wave‐trapping phenomenon. To circumvent those issues, we propose to use a thermodynamically‐consistent pressure‐disequilibrium model with finite, instead of infinite, pressure‐relaxation rate to overcome the difficulties inherent in the computation of these interactions. Because the original method to solve this model only enables infinite relaxation, we propose a new numerical method allowing infinite as well as finite relaxation rates. Solutions of the new modeling are examined and compared to literature, in particular we propose the study of a shock on a water–air interface, but also for problems of helium–air and water–air shock tubes, spherical and nonspherical bubble collapses. [ABSTRACT FROM AUTHOR]

Environmental noise has been regarded as major noise pollution with severe hazards to human physical and mental health. The common commercial fiber sound-absorption materials have insufficient low frequencies wave absorbing and fire-resistant ability, limiting their wide application. To solve these problems, a novel strategy combining flexible nanofibers and rGO/MXene nanosheets was proposed to fabricate rGO/MXene/SiO 2 nanofibers composite aerogel with hierarchically porous structure, which possessed an extremely low density of 9.8 mg/cm3 and superior low-frequency sound absorption ability (NRC value of 0.51). The obtained composite aerogel possessed a large deformation up to 80% (corresponding compressive stress of 17 kPa) and quickly recovered. In addition, the as-prepared aerogel could be easily produced on a large scale, providing a reference for the development of new generation of sound-absorbing products. [ABSTRACT FROM AUTHOR]

Simultaneously stretchable and compressible flexible strain sensors are highly desired in many advanced applications including the wearable field. However, the fabrication of such dual-function sensors with a wide sensing range is still challenging. In this work, a simultaneously stretchable and compressible foam strain sensor was fabricated by skillfully introducing oriented pores into the highly stretchable elastic composite based on carbon nanotubes and poly-(styrene-b-ethylene–butylene-b-styrene) (SEBS) by a freeze-drying method, in which cyclohexane was employed as the freeze-drying solvent. The high stretchability of SEBS and the abundant compressible space imparted by the pores endowed the resultant flexible foam sensor with highly stretchable (250%) and compressive (−50%) characteristics simultaneously. Thanks to the outstanding flexible features, the foam sensor enabled simultaneous monitoring of multiple human movements, such as bidirectional wrist bending, knee bending, foot stepping, and so forth. The foam sensor could encrypt human gesture signals into electrical signals and transmit them to the machine to realize the human–computer interaction, which could greatly broaden the application prospect of flexible strain sensors in the field of intelligent sensing. [ABSTRACT FROM AUTHOR]

In this paper, long-wave anti-plane shear motion in a multilayered laminate composed of pre-stressed compressible elastic layers is investigated. The layers of the laminate are perfectly bonded, while a fixed-free boundary condition is prescribed on the outer faces of the laminate. The solution of the model is determined analytically via the propagator matrix and numerically through the asymptotic approach. Moreover, the numerical results featuring harmonic curves are presented graphically, together with an asymptotic long-wave analysis of the vibration modes. As a special case of materials, linear isotropic with one shear modulus is considered. A polynomial long-wave low-frequency approximation of the related dispersion relation is also studied. It governs dispersion curves including the lowest harmonic. It is revealed that a low-frequency mode exists in both the two- and three-layered laminates, which are taken as prototypical structures. Lastly, comparisons between the exact and approximate asymptotic results are presented, and excellent agreement is observed. [ABSTRACT FROM AUTHOR]

Spherical crystallization is a technique in which crystallization and agglomeration are carried out synchronously in one step to form compact spherical form. The most common methods used in spherical agglomeration are quasi emulsion solvent diffusion method, ammonia diffusion system, neutralization technique and co-agglomeration. It succeeded to improve dissolution property of poorly soluble drugs. This can change drug powder properties such as flowability, wettability, packability, compressibility. It has wider applications in improvement of poorly compressible drugs; it has wider application in improvement of compressability of poorly compressible drugs, masking bitter taste of drugs, improving dissolution property, bioavailability and solubility of drugs. Agglomeration crystals converted into tablet forms thus helping us by saving time and reducing cost. [ABSTRACT FROM AUTHOR]

In this paper, the propagation of interfacial waves at the joint boundary of two initially stressed compressible half-spaces is discussed. The materials are subject to pure homogeneous strain and the wave is assumed to travel along one of the principle axes. For mathematical formulation of the problem, non-linear theory of elasticity and theory of invariants are used. Boundary conditions at the interface are applied which lead to an implicit secular equation governing the wave speed. A prototype strain-energy function is used for specialized theoretical results to understand the physical behavior of waves at the interface. A special case of biaxial initial stress is considered and the results are presented theoretically and graphically for representative numerical values of parameters. It is observed that the wave speed is considerably affected by intrinsic properties, i.e., material parameters as well as the amount of initial stress. [ABSTRACT FROM AUTHOR]

Sharp corners or wedges are common in everyday structures. Depending on the internal angle θ 0 of the wedge, severe stress concentration can occur. Linear elasticity predicts that when an incompressible elastic wedge is bonded to a rigid substrate and subjected to plane strain deformation, the stresses at the wedge tip has a power law singularity if θ 0 > 45 ∘ . For some θ 0 and for compressible wedges, the stresses are not only singular but oscillate infinitely rapidly. Here we show that these results are no longer true if large deformation is taken into consideration. Specifically, we determine the asymptotic fields near a tip of a Blatz–Ko wedge and found that the stress field has no power singularity for θ 0 ≤ 90 ∘ . Furthermore, the power law singularity of the stress field differs from those predicted by linear elasticity and there are no oscillations. For sufficiently low compressibility, it is possible to obtain higher order terms of the asymptotic series—analogous to William's expansion in linear theory. Our asymptotic results are validated by finite element calculations. We also studied the wedge tip field for the borderline case of a 90° wedge. For this case, the stress singularity is found to be at most logarithmic. [ABSTRACT FROM AUTHOR]

A spacetime formulation is presented to solve unsteady aerodynamic problems involving large deformation or topological change such as store separation, slat and flap deployment or spoiler deflection. This technique avoids complex CFD meshing methods, such as Chimera, by the use of a finite-volume approach both in space and time, and permits a locally varying real timestep. The use of a central-difference scheme in the time direction can yield non-physical transient solutions as a consequence of information travelling backwards in time. Therefore, an upwind formulation is provided and validated against one-dimensional and two-dimensional test cases. A hybrid formulation (central in space, upwind in time) is also given and unsteady cases are computed for a spoiler and spoiler/flap deployment, with all three formulations compared, demonstrating that the use of an upwind time stencil yields more representative physical solutions and improves the rate of convergence. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with the uniform regularity estimates of smooth solutions to the isentropic compressible magneto-micropolar system in . Under the assumption that , and by applying the classic bilinear commutator and product estimates, the uniform estimates of solutions to the isentropic compressible magneto-micropolar system are established in space, .

The engraving technique has grown in parallel with our human civilization, along with the targeted materials evolving from stone and metals to wood. Benefiting from the blossom of nanotechnology, the bulky nicking tools have downsized themselves to a micro-/nanoscale, such as laser beams, and the materials have been extended from traditional hard ones to soft functional nanomaterials. When ancient sculpture art meets modern advanced micro-/nano fabrication techniques and low-dimensional materials, impossible materials are born, which will redefine the functional scope of well-developed materials. Recently, a team from Tsinghua University reported such fascinating materials, graphene-based meta-aerogels, that process excellent elasticity, ultralight specific weight (down to 0.1 mg·cm−3), and superwide Poisson's ratio range (−0.95 vpeak

Low density, heat‐resistant sponge‐like fiber assembly materials are considered as promising high‐temperature insulation materials. However, the poor structural stability, infrared radiation heat transfer, and complex preparation process limit its further application. Herein, a facile method to create ultralow‐density ZrO2–TiO2 fiber sponges by the electrospinning method followed by heat treatment is presented. The layered structure sponges treated at 1200 °C have a low density of 9.5 mg cm−3. Moreover, the sponges possess high compressibility and good compression resistance over a wide temperature range from −196 to 1200 °C. In addition, the sponges exhibit low thermal conductivity of 27 mW m−1 K−1, robust fire resistance, and high near‐infrared reflectance, making them an ideal alternative for high‐temperature thermal insulation materials. [ABSTRACT FROM AUTHOR]

Uniform regularity plays an important role in the global existence of strong solutions and large time behavior of global solutions. In this work, we prove the uniform regularity of smooth solutions to the compressible flow of a chemically reacting gaseous mixture in T³. [ABSTRACT FROM AUTHOR]

• A coupled high-order monotonicity-preserving interface capturing scheme for computations of compressible three-phase flows with phase changes is presented. • Numerical results are validated against experimental data. • The characteristics of bubble interactions with a free surface and parallel walls are discussed. • The effects of the initial pressure and non-condensable gas volume fraction on the behavior of the explosion bubble are analyzed. The complex dynamics of two flow problems of vapor explosion bubbles near a free surface and between two parallel plates are simulated by a compressible three-phase flow code. Firstly, a coupled high-order monotonicity-preserving (MP) interface capturing scheme is developed for the numerical computation of compressible three-phase flows, which is followed by validation with previous numerical and experimental data. Phase changes are taken into consideration and the empirical condensation coefficient is calibrated with the experimental data. For both two flow problems, good agreement between the numerical results and reference data is obtained. Most physical phenomena, including the free surface spike, the liquid jet before the impact and the complex interface deformations during multiple expanding and collapsing oscillations, are reasonably well reproduced. Afterwards, the effects of the initial vapor pressure and the non-condensable gas volume fraction in the surrounding water on the behavior of vapor bubbles are analyzed and discussed. It is found that both the initial vapor pressure and the non-condensable gas volume fraction have a substantial influence on the behavior of the bubble. Higher initial vapor pressure does indeed tend to result in larger bubbles. The presence of non-condensable gases tends to hinder the transfer of heat, slowing down condensation and potentially resulting in larger bubbles. When the initial vapor pressure is in the range of 10 to 20 atmospheres and the gas volume fraction is in the range of 0 to 0.2, the maximum vapor bubble volume is found to increase linearly with an increase of the amount of non-condensable gas. [ABSTRACT FROM AUTHOR]

In this work, we prove the uniform regularity of smooth solutions to an Ericksen–Leslie's parabolic–hyperbolic liquid crystals model in a three-dimensional torus. [ABSTRACT FROM AUTHOR]

The performance of the engine highly depends on the fuel mixing process as a significant process to achieve efficient supersonic flight. Current article has attempted to release the effects of different annular lobe-injectors on fuel mixing when Ma >1. Three various annular jet nozzles are expansively investigated for injection of the sonic hydrogen jet at supersonic air crossflow with Mach-4. Comprehensive comparison of the jet structure of these models are performed through the evaluation of Mach and fuel concentration downstream of these lobe-injectors. Comparison of mixing efficiency also indicates that the nozzle with 3-lobe configuration has 25% more fuel mixing performance than other configurations. Our findings also show that mixing performance of annular lobe-injector is about 15% more than simple one for cases with 2-lobe and 4-lobe injectors. • Influence of annular lobe-injector on the fuel mixing of hydrogen jet at supersonic flow is studied. • The mixing performance of the air/fuel jets in various jet conditions is investigated. • Effect of various profiles of shock generator on flame distribution is entirely investigated. • CFD approach is applied for the simulation of the co-jets with sinusoidal shock generator. [ABSTRACT FROM AUTHOR]

MONOLITh is a bioinspired, untethered crawling soft robot. The body is made from a lightweight reticulated foam that provides passive shape restoration and supports the internally embedded components (motors, battery, wireless controller). DC motors pull tendons attached to an external fabric that distributes forces, and novel differential friction elements enable forward locomotion. This robot is capable of traveling at a maximum speed of 0.1 body lengths/sec, lifting 100% of its body weight, while remaining 95% soft materials by volume. We expect that the design principles and materials used to make this low cost and scalable robot will lead to the development of useful, and commercially viable, terrestrial or extraterrestrial vehicles. [ABSTRACT FROM AUTHOR]

Land subsidence is a global threat to coastal areas worldwide, including the North Java coastal area. Of many areas experiencing land subsidence in North Java, the rate of land subsidence in Pekalongan has matched the high subsidence rates usually found in big cities. The rate of land subsidence in Pekalongan far exceeds the sea-level rise, resulting in a looming threat of land loss. The devastating impacts of land subsidence are the manifestation of its subsurface movement. Therefore, it is essential to understand the subsurface to elucidate the mechanism of land subsidence. Previous studies on land subsidence in Pekalongan are mainly related to subsidence rate monitoring and have not elaborated on the subsurface condition. This paper reviews the Pekalongan subsurface geology based on available literature to provide insight into the land subsidence problem. The results revealed that the land subsidence occurs in the recent alluvial plain of Pekalongan, consisting of a 30-70 m thick compressible deposit. Possible mechanisms of land subsidence arise from natural compaction, over-exploitation of confined groundwater, and increased built areas. As the seismicity of the study area is low, tectonic influence on land subsidence is considered negligible. It is expected that the offshore, nearshore, and swamp deposits are still naturally compacting. As the surface water supply is minimal, over-exploitation of groundwater resources from the deltaic and Damar Formation aquifers occurs. In the end, future research direction is proposed to reduce the impacts of the subsidence hazard.

Tornado is a destructive catastrophe. We use compressible isentropic Euler equations to describe this problem. A cylindrically symmetric special solution moving with a constant velocity in R 3 is given. It depicts how the vorticity function of the flow evolves. Even if the initial inward velocity and acceleration are both very small, the inward velocity could become very large and the vorticity could increase drastically in later time, and most of mass concentrates on a neighborhood of the moving center axis at this time. For this solution, cases when γ ≠ 2 and when γ = 2 (shallow water) have some differences, while their evolution dynamics are basically the same. When γ = 2 , the initial vorticity could depend on the space variables. [ABSTRACT FROM AUTHOR]

[Display omitted] • Develop a portable solar evaporator that can save storage space more than 78%. • Hyperstable plant fibers/chitosan aerogel is constructed without toxic cross-linkers/solvents. • The solar evaporator can endure tremendous and repeated compression over 100 times. • The evaporator is cost-effective and salt-rejecting, working well under various harsh conditions. • High evaporation rate of 1.38 kg m-2 h−1 and solar-to-vapor conversion efficiency of 84.27%. Solar interfacial evaporation is an effective zero-energy method for seawater desalination, and solar evaporator is the key component in this evaporation system. Despite a great deal of solar evaporators have been reported, the poor portability of large-scale evaporators as well as high costs and materials toxicity still restrict their applications. In this work, a portable solar evaporator was constructed with low-cost plant fibers from papermaking pulp, using a facile method in absence of any toxic cross-linkers and solvents. The evaporator exhibited excellent stability and flexibility, and endured tremendous and repeated compression over 100 times. A large-scale evaporator could be compressed to reduce storage space by 78%, which would be portable for individuals. The evaporator presented a high evaporation rate of 1.38 kg m-2h−1, and solar-to-vapour conversion efficiency of 84.27% under one sun irradiation. The portable solar evaporator was salt-rejecting, and worked well under harsh conditions of high salinity and different pH values. The entire material cost of this potable solar evaporator is approximately 1.75 U.S. dollar m−2, much lower than those of conventional solar evaporators. This study provides a new approach for preparing portable and cost-effective solar evaporator. [ABSTRACT FROM AUTHOR]

We study the impact of compressibility on two-dimensional turbulent flows, such as those modeling astrophysical disks. We demonstrate that the direction of cascade undergoes continuous transition as the Mach number Ma increases, from inverse at Ma = 0, to direct at $Ma = \infty$ . Thus, at $Ma \sim 1$ comparable amounts of energy flow from the pumping scale to large and small scales, in accord with previous data. For supersonic turbulence with $Ma \gg 1$ the cascade is direct, as in three dimensions, which results in multifractal density field. For that regime ( $Ma \gg 1$ ) we derive a Kolmogorov-type law for potential forcing and obtain an explicit expression for the third order correlation tensor of the velocity. We further show that all third order structure functions are zero up to first order in the inertial range scales, which is in sharp contrast with incompressible turbulence where the third order structure function, that describes the energy flux associated with the energy cascade is non-zero. The properties of compressible turbulence have significant implications on the amplification of magnetic fields in conducting fluids. We thus demonstrate that imposing external magnetic field on compressible flows of conducting fluids allows to manipulate the flow producing possibly large changes even at small Mach numbers. Thus Zeldovich’s antidynamo theorem, by which at Ma = 0 the magnetic field is zero in the steady state, must be used with caution. Real flows have finite Ma and, however small it is, for large enough values of I , the magnetic flux through the disk, the magnetic field changes the flow appreciably, or rearranges it completely. This renders the limit Ma → 0 singular for non-zero values of I . Of particular interest is the effect of the density multifractality, at $Ma\gg 1$ which is relevant for astrophysical disks. We demonstrate that in that regime, in the presence of non-zero I the magnetic field energy is enhanced by a large factor as compared to its estimates based on the mean field. Finally, based on the insights described above, we propose a novel two-dimensional Burgers’ turbulence, whose three-dimensional counterpart is used for studies of the large-scale structure of the Universe, as a model for supersonic two-dimensional magnetohydrodynamic flows.