当前期刊: Physics of Fluids Go to current issue    加入关注   
显示样式:        排序: 导出
我的关注
我的收藏
您暂时未登录!
登录
  • Scale invariance and ε expansion in the RNG theory of stirred fluids
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    D. Carati, K. Chriaa

    The influence of a ‘‘nonscale invariant’’ forcing is investigated in the renormalization group theory of stirred fluids. It is shown that such forcings introduce a free parameter in the theory. However, the difficulties inherent in the use of the ε expansion remain when the results are applied to real turbulence.

    更新日期:2020-03-04
  • Chaotic motion of a solid through ideal fluid
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Hassan Aref, Scott W. Jones

    Numerical evidence is presented that the motion of a solid body through incompressible, inviscid fluid, moving irrotationally and otherwise at rest, is chaotic.

    更新日期:2020-03-04
  • Two‐ and three‐dimensional models for flow through a junction
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    K. B. Ranger

    Two‐ and three‐dimensional models of the fluid motion through a junction are described for Stokes flow. It is found that for both models separation of the streamlines can occur on the branch of the outer channel wall with smaller flow rate. The relevance of the results for flow at higher Reynolds numbers is also described.

    更新日期:2020-03-04
  • Wave formation in the gravity‐driven low‐Reynolds number flow of two liquid films down an inclined plane
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    KangPing Chen

    Wave formation in the gravity‐driven low‐Reynolds number flow of two liquid films down an inclined plane is studied by a linear stability analysis. Wavy motion can appear due to an instability of either the fluid–fluid interface or the fluid‐air free surface. It is shown that the flow is always unstable and wavy motion can occur when the less viscous layer is in the region next to the wall for any

    更新日期:2020-03-04
  • The transition in the sedimentation pattern of a particle cloud
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Y. Noh, H. J. S. Fernando

    Experiments were carried out to study the sedimentation of a two‐dimensional particle cloud. When a large number of particles (glass beads) of uniform size are released from a two‐dimensional opening into a column of fresh water, the mixture initially descends as a thermal; however, after some time, the particles start settling individually, thus leaving the parent fluid behind. For a given type of

    更新日期:2020-03-04
  • Hydrodynamic modes of a uniform granular medium
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Sean McNamara

    This paper uses a fluid‐mechanical model of a granular medium to calculate the hydrodynamic modes of a spatially uniform basic state. These modes are the granular analogs of the heat, sound, and shear modes of the standard fluid. Attention is focused on the possibility of an unstable mode that might result in the spontaneous development of inhomogeneities in density. Two cases are considered: the cooling

    更新日期:2020-03-04
  • Resonance of longshore currents under topographic forcing
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    A. Falqués, V. Iranzo, A. Montoto

    The steady perturbation caused in a longshore flow by a bottom undulation is considered. The bedforms are assumed to be alongshore periodic, with crests in the cross‐shore direction and with a small amplitude in order for linear theory to be applicable. The inviscid shallow‐water equations are considered in order to investigate topographic resonance, that is, the condition under which the perturbation

    更新日期:2020-03-04
  • A theoretical study of polydisperse liquid sprays in a shear‐layer flow
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    D. Katoshevski, Y. Tambour

    A shear layer formed by two unidirectional gas streams of different velocities with a multisize (polydisperse) spray of evaporating droplets suspended in one of the gas streams is considered here. Similarity solutions are presented for the evolution in droplet size distributions across the shear layer and the effects of various initial droplet size distributions on the profiles of vapor concentrations

    更新日期:2020-03-04
  • The unsteady structure of two‐dimensional steady laminar separation
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Matthew D. Ripley, Laura L. Pauley

    The two‐dimensional unsteady incompressible Navier–Stokes equations, solved by a fractional time‐step method, were used to investigate separation due to the application of an adverse pressure gradient to a low‐Reynolds number boundary layer flow. The inviscid pressure distribution of Gaster [AGARD CP 4, 813 (1966)] was applied in the present computations to study the development of a laminar separation

    更新日期:2020-03-04
  • On the spatial stability of tube flows subject to body forces
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    D. J. Goering, J. A. C. Humphrey

    The spatial stability of multiple solutions for fully developed laminar flow through a curved tube and through a straight tube in the presence of buoyant effects was studied using a three‐dimensional numerical representation of the fully elliptic Navier–Stokes and energy equations. Several recent numerical studies have reported the existence of multiple solutions for fully developed laminar flow in

    更新日期:2020-03-04
  • Nonaxisymmetric instability in slowly swirling jet flows
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    M. R. Foster

    Very small amounts of swirl are shown to strongly destabilize a round jet flow to large n inertial modes, where (k,n) are, respectively, the axial and azimuthal wave numbers of the disturbance. This mechanism is operative if the scale of the small swirl, ε, is O(n−1) for k=O(1). Further, viscosity is shown to exert a stabilizing influence on these modes if the Reynolds number is no larger than O(n3)

    更新日期:2020-03-04
  • On the stability of nonisothermal circular Couette flow
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    A. A. Kolyshkin, Rémi Vaillancourt

    The stability of a circular Couette flow with internal heat generation is studied in the region between two coaxial cylinders. The inner cylinder is rotating with constant velocity while the outer one is kept at rest. The investigation is carried out for wide ranges of the Prandtl number and radius ratio R, for the axisymmetric mode (n=0) and the first two asymmetric modes (n=1,2), respectively. For

    更新日期:2020-03-04
  • Study of the parametric oscillator driven by narrow‐band noise to model the response of a fluid surface to time‐dependent accelerations
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Wenbin Zhang, Jaume Casademunt, Jorge Viñals

    A stochastic formulation is introduced to study the large amplitude and high‐frequency components of residual accelerations found in a typical microgravity environment (or g‐jitter). The linear response of a fluid surface to such residual accelerations is discussed in detail. The analysis of the stability of a free fluid surface can be reduced in the underdamped limit to studying the equation of the

    更新日期:2020-03-04
  • Wall reflections of solitary waves in Marangoni–Bénard convection
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    H. Linde, X.‐L. Chu, M. G. Velarde, W. Waldhelm

    In Marangoni–Bénard convection with mass transfer from the air to the liquid, an experimental exploration of reflections of solitary waves at walls has been carried out. Mach stems are observed for small enough incident angles. Upon increasing the incident angle the stem disappears thus leading to regular reflections with, however, the angle of reflection being generally larger than the incident angle

    更新日期:2020-03-04
  • Corewise cross‐flow transport in hairpin vortices—The ‘‘tornado effect’’
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    J. P. Hagen, M. Kurosaka

    There is increasing awareness that even in fully turbulent boundary layers, large‐scale structures in the form of hairpin vortices abound. Although their implications are not all that clear at the present time, they seem to play an important role in turbulent flows. Due to the inherent unpredictability of hairpin vortices in their natural state, in the past effort has been made to generate synthetic

    更新日期:2020-03-04
  • The effect of slowly varying gap width on Dean vortices
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    P. M. Eagles

    Taylor–Dean vortices are considered in channels whose thickness and curvature vary slowly on a scale 1/δ. The effect of divergence of the channel is shown to be destabilizing and of convergence to be stabilizing. Results for neutral curves are presented for a class of particular channels, and a method of computing such curves for more general channels is given.

    更新日期:2020-03-04
  • Self‐similarity and multifractals in turbulence
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Michael S. Borgas

    A simple argument based on self‐similarity is used to derive a relationship between pointwise energy‐dissipation‐rate moments, 〈εq〉, and inertial‐range volume‐averaged moments, 〈εqr〉, in homogeneous, isotropic and stationary turbulence. These results support the multifractal description of energy dissipation. The moment relationship implies that pointwise and inertial‐range volume‐averaged energy‐dissipation

    更新日期:2020-03-04
  • A dynamic mixed subgrid‐scale model and its application to turbulent recirculating flows
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Yan Zang, Robert L. Street, Jeffrey R. Koseff

    The dynamic subgrid‐scale eddy viscosity model of Germano et al. [Phys. Fluids A 3, 1760 (1991)] (DSM) is modified by employing the mixed model of Bardina et al. [Ph.D dissertation, Stanford University (1983)] as the base model. The new dynamic mixed model explicitly calculates the modified Leonard term and only models the cross term and the SGS Reynolds stress. It retains the favorable features of

    更新日期:2020-03-04
  • The influence of linear mechanisms during the adjustment of sheared turbulence to flow curvature
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    A. G. L. Holloway, R. Gupta

    Recent experimental studies on homogeneous curved shear flow have shown that the imposition of strong mean flow curvature can cause a reversal of the turbulent shear stress, giving it the same sign as the gradient of mean velocity. Measurements of the coherence spectrum for these flows has revealed that this reversal is not uniform across all scales, and that eddies of different sizes can have opposite

    更新日期:2020-03-04
  • Conditional scalar dissipation rates in turbulent wakes, jets, and boundary layers
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    P. Kailasnath, K. R. Sreenivasan, J. R. Saylor

    The expected value Eχ≡E(χ,θ=θ0) of the dissipation rate χ of a passive scalar θ conditioned on the scalar value θ=θ0 has been measured in three varieties of turbulent shear flows: heated wakes, dyed liquid jets, and the atmospheric surface layer. The quantity Eχ depends fairly strongly on θ0 and on the flow. For the wake, Eχ exhibits two peaks—one on the low‐temperature end and the other on the high‐temperature

    更新日期:2020-03-04
  • Turbulent structure and entrainment in heated jets: The effect of initial conditions
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    S. Russ, P. J. Strykowski

    The turbulent structure in the near field of heated jets was investigated at a Reynolds number of 10 000 for density ratios between 1.0 and 0.5; the corresponding mixing and entrainment of these low density jets was examined. The exit conditions of the jet were carefully controlled using extension tubes to alter the nozzle‐exit boundary layer thickness, as well as using screens to generate turbulent

    更新日期:2020-03-04
  • Vortical nature of thermal plumes in turbulent convection
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    T. Cortese, S. Balachandar

    Thermal plumes in Rayleigh–Bénard convection have been observed to occur with strong vertical component of vorticity, resulting in spiraling hot updrafts and cold downdrafts. Results from two different simulations at Rayleigh numbers 9800 and 33 000 times the critical Rayleigh number close to the boundaries show rapid increase in the conditional averages of vertical velocity and temperature perturbation

    更新日期:2020-03-04
  • Turbulent transport in wall‐bounded flows. Evaluation of model coefficients using direct numerical simulation
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    J. B. Cazalbou, P. Bradshaw

    The modeling of the turbulent diffusion of quantities such as the turbulent kinetic energy and its dissipation rate in the outer part of wall‐bounded flows is examined with the aid of simulation data. The channel‐flow data of Mansour et al. [J. Fluid Mech. 194, 15 (1988)] and those of Spalart [J. Fluid Mech. 187, 61 (1988)] for a flat‐plate boundary layer with zero pressure gradient are used to examine

    更新日期:2020-03-04
  • Statistical analysis of the rate of strain tensor in compressible homogeneous turbulence
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    G. Erlebacher, S. Sarkar

    Recent analysis of direct numerical simulations of compressible homogeneous shear flow turbulence has unraveled some of the energy transfer mechanisms responsible for the decrease of kinetic energy growth when the flow becomes more compressible. In this complementary study, attention is focused on the rate of strain tensor. A Helmholtz decomposition of the velocity field leads to a consideration of

    更新日期:2020-03-04
  • Measurement and prediction of the conditional variance in a turbulent reactive‐scalar mixing layer
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    J. D. Li, R. W. Bilger

    Equations for the second‐order conditional moments of reactive scalars are derived. For one‐step reaction with equal diffusivity these can be reduced to a single equation for the conditional variance, which is the same for all reactive species. The various terms in the equation have been modeled in light of the experimental data for a turbulent reactive‐scalar mixing layer. In comparison with conventional

    更新日期:2020-03-04
  • The sudden expansion of a gas cloud into vacuum revisited
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Y. Tzuk, B. D. Barmashenko, I. Bar, S. Rosenwaks

    The sudden expansion into vacuum of a gas cloud, with initial centrally symmetric density and temperature profiles, is studied theoretically for different values of the specific heat ratio γ. Models treating the expansion are discussed, in particular, a model for isentropic expansion and a model for spatially isothermal expansion. For γ→1, the density of the gas obtained from the former model for late

    更新日期:2020-03-04
  • Convective heat transfer through polarized dielectric liquids
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    P. J. Stiles, F. Lin, P. J. Blennerhassett

    An electrically insulating layer of a dielectric liquid confined between horizontal conducting electrodes, the upper of which is warmer, becomes unstable with respect to the onset of steady convection when the voltage between the plates reaches a critical value. In a rapidly varying ac field this instability is due to the Kelvin body force which depends on the polarization P and the gradient of the

    更新日期:2020-03-04
  • The use of magnetohydrodynamic effects to investigate fluid flow in electrically conducting melts
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    J. Baumgartl, A. Hubert, G. Müller

    A measurement method is introduced which can detect steady and unsteady flow in electrically conducting fluids. In this method, the flow region is subjected to an externally applied weak magnetic field B0. The induced magnetic field b generated by fluid flow across the field lines of B0 is used for the flow investigations. It can be measured outside the flow region with the advantage that neither electrical

    更新日期:2020-03-04
  • A note on the force on an accelerating spherical drop at low‐Reynolds number
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    V. Galindo, G. Gerbeth

    The time‐dependent drag force on a spherical drop is analyzed for the linear limit of small Reynolds numbers. There is an error in literature on the generalization of the known Basset memory kernel of a rigid sphere to the case of a drop. Correct results are presented here. A new overshooting effect is found if thermocapillarity is driving the drop motion rather than gravity.

    更新日期:2020-03-04
  • A note on the asymmetry of rotating, stratified flow past a shallow ridge
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Kiran B. Chilakamarri, M. R. Foster, Peter Hamburger

    Streamline patterns in experiments of Boyer and Biolley [Philos. Trans. R. Soc. London Ser. A 318, 411 (1986)] on flow past a shallow ridge on the floor of a channel in a rotating, stratified fluid exhibit a clear upstream/downstream asymmetry. In this note this question is considered and also a condition for the existence of an eddy in such flows is derived by examining the mathematical properties

    更新日期:2020-03-04
  • Vortex shedding from long slender cylinders in near‐axial flow
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    M. K. Bull, W. A. Dekkers

    It has been found that vortex shedding can occur from long cylinders at small angles of yaw, i.e. in near‐axial flow. The range of Reynolds number over which this can take place has been determined for yaw angles between 0° and 10°. Results for vortex‐shedding frequencies are also presented, and compared with existing data for larger yaw angles. It is suggested that the phenomenon may be relevant to

    更新日期:2020-03-04
  • The decay of a pair of point vortices in a viscous fluid
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Samuel Ohring, Hans J. Lugt

    The decay of two counter‐rotating point vortices of equal strength in a viscous incompressible fluid is studied by solving the Navier–Stokes equations with a finite‐difference technique. Solutions for Reynolds numbers 10, 50, and 100 are compared with a model presented by Cantwell and Rott. Equivorticity lines and the decay rate of translational velocity and circulation of the half‐plane are presented

    更新日期:2020-03-04
  • A nonequilibrium representation of the turbulent viscosity based on a two‐scale turbulence theory
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Akira Yoshizawa, Shoiti Nisizima

    A nonequilibrium expression of the turbulent viscosity in the Reynolds stress is proposed with the aid of the results from a two‐scale direct‐interaction approximation. The usual turbulent‐viscosity model based on the turbulent kinetic energy K and its dissipation rate ε is extended to include their nonequilibrium effects DK/Dt and Dε/Dt (D/Dt is the Lagrange derivative based on the mean velocity)

    更新日期:2020-03-04
  • A note on turbulent energy dissipation in the viscous wall region
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Peter Bradshaw, J. Blair Perot

    From simulation data it is shown that the difference between the true rate of dissipation of turbulent kinetic energy and the ‘‘isotropic dissipation’’ used by Reynolds‐averaged modelers is less than 2% in a conventional viscous wall region, and negligible elsewhere. The difference is a contribution to viscous diffusion which is a small fraction of the total.

    更新日期:2020-03-04
  • On the relation of near‐wall streamwise vortices to wall skin friction in turbulent boundary layers
    Phys. fluids (IF 2.627) Pub Date : 1998-06-04
    Arthur G. Kravchenko, Haecheon Choi, Parviz Moin

    Databases from direct numerical simulations of fully developed turbulent channel flow were used to examine the relation between skin‐friction on the wall and streamwise vortices observed near the wall. It is shown that the wall shear rate correlates with streamwise vortices near the wall and that the maximum correlation occurs downstream and with lateral displacement from the location of skin‐friction

    更新日期:2020-03-04
  • Radial deformation and disintegration of an electrified liquid jet
    Phys. fluids (IF 2.627) Pub Date : 2020-02-19
    Fang Li; Shiyou Ke; Shumin Xu; Xieyuan Yin; Xiezhen Yin

    Droplets stretched by electric stresses emit jets from their pointed tips. We observed in the experiment a new tip-streaming phenomenon by applying a radial electric field to a liquid jet. Droplets in the jet are stretched in the radial direction and develop into a disk-like shape. The growth of non-axisymmetric harmonics leads to the formation of tens of Taylor cones evenly distributed at the equator

    更新日期:2020-02-28
  • An experimental model for pressure drop evaluation in a stenosed coronary artery
    Phys. fluids (IF 2.627) Pub Date : 2020-02-03
    Navid Freidoonimehr, Rey Chin, Anthony Zander, Maziar Arjomandi

    Non-invasive measurement of pressure drop has great clinical significance for the treatment of coronary artery diseases. The objective of this study is to develop a relationship that can estimate pressure drop in a stenosed coronary artery model as a function of different parameters such as blood viscosity, artery length and diameter, flow rate and flow profile, and shape and degrees of stenosis. Experimental

    更新日期:2020-02-28
  • Dynamics of a microswimmer–microplatelet composite
    Phys. fluids (IF 2.627) Pub Date : 2020-02-05
    Abdallah Daddi-Moussa-Ider, Maciej Lisicki, Hartmut Löwen, Andreas M. Menzel

    Guiding active microswimmers by external fields to requested target locations is a promising strategy to realize complex transport on the microscale. For this purpose, one possibility consists of attaching the microswimmers to orientable passive components. Accordingly, we analyze theoretically, using a minimal model, the dynamics of a microswimmer when rigidly attached to a (significantly larger)

    更新日期:2020-02-28
  • Hydrodynamic behavior of two-dimensional tandem-arranged flapping flexible foils in uniform flow
    Phys. fluids (IF 2.627) Pub Date : 2020-02-10
    Liang Cheng

    Hydrodynamic behavior of two-dimensional tandem-arranged flapping flexible foils in uniform flow is investigated numerically by an immersed boundary-lattice Boltzmann method. The leading edge of the leading foil is forced to undergo both heave and pitch motions, while the leading edge of the trailing foil is forced to undergo heave motion only. Of particular interests are the effects of stream-wise

    更新日期:2020-02-28
  • Ceiling effects on the aerodynamics of a flapping wing with advance ratio
    Phys. fluids (IF 2.627) Pub Date : 2020-02-12
    Xueguang Meng; Yang Zhang; Gang Chen

    The ceiling effect on the aerodynamics of flapping wings with an advance ratio is investigated by solving the three-dimensional incompressible Navier–Stokes equations. The aerodynamic forces and flow fields around the model wings flapping in a horizontal plane were simulated at various advance ratios, Reynolds numbers, as well as the distance between the wing and the ceiling. It is found that the ceiling

    更新日期:2020-02-28
  • Tip vortices formation and evolution of rotating wings at low Reynolds numbers
    Phys. fluids (IF 2.627) Pub Date : 2020-02-14
    Chengyu Li, Haibo Dong, Bo Cheng

    The wake structures generated by rotating wings are studied numerically to investigate the complex vortex formation and evolution in both near-wake and far-wake regions. Flat rectangular wings with finite aspect ratios (AR = 1–8) that rotate from rest at an angle of attack ranging from 15° to 90° in a low Reynolds number regime (200–1600) are considered. Simulations were carried out using an in-house

    更新日期:2020-02-28
  • A self-propelled flexible plate with a Navier slip surface
    Phys. fluids (IF 2.627) Pub Date : 2020-02-20
    Shuai Wang; Jaeha Ryu; Guo-Qiang He; Fei Qin; Hyung Jin Sung

    The hydrodynamics of a three-dimensional self-propelled flexible plate with a Navier slip surface was explored in an effort to assess its role in the hydrodynamics of a slip boundary that mimics the mucus layer. The Navier slip arises when the component of the tangential velocity at a wall is proportional to the strain. The immersed boundary method was employed to simulate the flow. For comparison

    更新日期:2020-02-28
  • Modified Boltzmann equation and extended Navier–Stokes equations
    Phys. fluids (IF 2.627) Pub Date : 2020-02-04
    Kumar Nawnit

    We refine the derivation of the Boltzmann equation by considering that the molecules passing through the interfaces of a volume element of physical space and velocity space exhibit different velocity distribution functions and number densities. The resulting equation has a time parameter close to the relaxation time and degenerates into the conventional Boltzmann equation when this parameter takes

    更新日期:2020-02-28
  • Influence of non-hydrodynamic forces on the elastic response of an ultra-thin soft coating under fluid-mediated dynamic loading
    Phys. fluids (IF 2.627) Pub Date : 2020-02-04
    P. Karan, J. Chakraborty, S. Chakraborty

    The force between two approaching solids in a liquid medium becomes increasingly large with decreasing separation—a phenomenon that prevents contact between the two solids. This growth in force occurs because of the intervening liquid, and studies of such physical systems constitute the classical discipline of lubrication. Furthermore, when the solid(s) are soft, there are quantitative as well as qualitative

    更新日期:2020-02-28
  • Magnetohydrodynamic natural convection flow of a nanofluid due to sinusoidal surface temperature variations
    Phys. fluids (IF 2.627) Pub Date : 2020-02-10
    Nepal Chandra Roy

    We examine the natural convection flow that arises in an electrically conducting nanofluid due to the sinusoidal surface temperature variations along a vertical surface. The effect of thermal radiation is also incorporated. The reduced system of governing equations is solved using an efficient implicit finite difference method which is also known as the Keller box method. The results are presented

    更新日期:2020-02-28
  • A study on mixing performance of dean flows through spiral micro-channel under various effects
    Phys. fluids (IF 2.627) Pub Date : 2020-02-11
    I. L. Ngo, T. K. Lai, H. J. Choi, H. T. T. Le, G. M. Kim, T. D. Dang

    This paper reports a parametric study on mixing performance of dean flows in spiral micro-channels using the finite element method. Many important parameters such as the Reynolds number (Re), Peclet number (Pe), flow rate ratio between two species flows (α), and ratio of diffusion coefficient (β) were examined for enhancing mixing efficiency (ηmix). The numerical results matched well with those predicted

    更新日期:2020-02-28
  • Theoretical investigation of electroviscous flows in hydrophilic slit nanopores: Effects of ion concentration and pore size
    Phys. fluids (IF 2.627) Pub Date : 2020-02-20
    Zhilin Cheng; Zhengfu Ning; Wentong Zhang; Shizhen Ke

    Nanopores with various shapes are well developed in unconventional reservoirs, and the transport phenomena of solutions in these reservoir rocks are ubiquitous but have not yet been fully understood. This article investigates the flow characteristics of solutions in hydrophilic slit nanopores through the combination of a modified Poisson–Boltzmann (MPB) model and the modified Navier–Stokes (NS) equation

    更新日期:2020-02-28
  • Large deformation of a conductive nanodroplet in a strong electric field
    Phys. fluids (IF 2.627) Pub Date : 2020-02-20
    Qichun Nie, Yongan Huang, Zhouping Yin, Haisheng Fang

    Despite their remarkable effect on printing accuracy and uniformity, charge migrations that dominate the deformation of ink droplets during electrohydrodynamic jet printing have not been widely investigated. In this work, the large deformation mechanisms of a conductive nanodroplet under a strong electric field are examined from the point of view of charge migrations. It is found that the charge migrations

    更新日期:2020-02-28
  • Analysis of drop-on-demand piezo inkjet performance
    Phys. fluids (IF 2.627) Pub Date : 2020-02-21
    Seung-Hwan Kang; San Kim; Dong Kee Sohn; Han Seo Ko

    For a particular printing ink and drop-on-demand piezoelectric inkjet printhead, piezoelectric voltage and temperature of the ink were varied to change the inkjet performance, and the jetting velocity of the inkjet was analyzed under various conditions. The ink was cooled by using a Peltier module, which was attached to the nozzle plate as a heat sink. The inkjet drops were captured by the shadowgraphic

    更新日期:2020-02-28
  • Inlet swirl decay and mixing in a laminar micro-pipe flow with wall slip
    Phys. fluids (IF 2.627) Pub Date : 2020-02-27
    Dhananjay Kumar, Shavitur Mukesh Kumar Shakya, P. Kaushik

    In this work, the decaying laminar inlet swirl flow in a straight circular micro-pipe with wall slip is solved analytically and the solution is verified numerically. Based on a fully developed parabolic axial velocity profile, the swirl velocity equation is solved by the separation of variables technique. The solution is expressed as a function of the flow Reynolds number, the axial distance within

    更新日期:2020-02-28
  • Dynamical wetting transition on a chemically striped incline
    Phys. fluids (IF 2.627) Pub Date : 2020-02-07
    Yuting Xia; Jian Qin; Peng Gao

    We study the dynamics of moving contact lines and film deposition on a chemically heterogeneous plate withdrawn from a liquid bath. The plate is patterned with vertical stripes characterized by alternating wettabilities. It is assumed that the interfacial slope with respect to the plate is small such that lubrication theory can be employed. The finite element method is used to solve the two-dimensional

    更新日期:2020-02-28
  • Effect of variation in density on the stability of bilinear shear currents with a free surface
    Phys. fluids (IF 2.627) Pub Date : 2020-02-21
    Ricardo Barros, José Felipe Voloch

    We perform the stability analysis for a free surface fluid current modeled as two finite layers of constant vorticity, under the action of gravity and absence of surface tension. In the same spirit as Taylor [“Effect of variation in density on the stability of superposed streams of fluid,” Proc. R. Soc. London, Ser. A 132, 499 (1931)], a geometrical approach to the problem is proposed, which allows

    更新日期:2020-02-28
  • Effect of aging time on the viscoelastic properties of amphiphilic polymer-polyacid supramolecular solution
    Phys. fluids (IF 2.627) Pub Date : 2020-02-03
    Bauyrzhan Sarsenbekuly

    An amphiphilic polymer-based supramolecular system was formulated by exploring the electrostatic interactions between the cationic amphiphilic polymer and polyacid. The effect of aging time on the viscoelastic properties, salt and temperature tolerance, shear resistance, and viscosity recovery of the system was explored by means of rheological measurements. The intrinsic relationship between the viscoelasticity

    更新日期:2020-02-28
  • Three-dimensional viscoelastic instabilities in a four-roll mill geometry at the Stokes limit
    Phys. fluids (IF 2.627) Pub Date : 2020-02-03
    Paloma Gutierrez-Castillo, Adam Kagel, Becca Thomases

    Three-dimensional numerical simulations of viscoelastic fluids in the Stokes limit with a four-roll mill background force (extended to the third dimension) were performed. Both the Oldroyd-B model and FENE-P model of viscoelastic fluids were used. Different temporal behaviors were observed depending on the Weissenberg number (non-dimensional relaxation time), model, and initial conditions. Temporal

    更新日期:2020-02-28
  • Mechanical characterization of the nitrocellulose-based visco-hyperelastic binder in polymer bonded explosives
    Phys. fluids (IF 2.627) Pub Date : 2020-02-03
    M. Iqbal, J. Y. S. Li-Mayer, D. Lewis, S. Connors, M. N. Charalambides

    A rheological constitutive model is required to characterize the behavior of a nitrocellulose-based material used as a binder in polymer bonded explosives. The behavior of the binder is extremely important as it heavily influences the mechanical response of the polymer composite; this is due to the binder having stiffness five orders of magnitude lower than the stiffness of the explosive crystals.

    更新日期:2020-02-28
  • Rheology of sodium and zinc ionomers: Effects of neutralization and valency
    Phys. fluids (IF 2.627) Pub Date : 2020-02-05
    Muaad Zuliki, Shiling Zhang, Kudzanai Nyamajaro, Tanja Tomkovic, Savvas G. Hatzikiriakos

    Using a parallel-plate rheometer equipped with a partitioned plate and the Sentmanat extensional rheometer fixture, a full rheological characterization of several commercial ionomers (sodium and zinc) and their corresponding parent copolymers has been carried out. Particular emphasis has been placed on the distribution of the relaxation times to identify the characteristic times, such as reptation

    更新日期:2020-02-28
  • Theoretical analysis of two-layered electro-osmotic peristaltic flow of FENE-P fluid in an axisymmetric tube
    Phys. fluids (IF 2.627) Pub Date : 2020-02-07
    N. Ali, S. Hussain, K. Ullah

    This article presents the theoretical analysis of two-dimensional peristaltic transport of two-fluids in a flexible tube under the influence of electro-osmotic force. The flow domain is composed of two regions, namely, the core region and the peripheral region. The Newtonian and the FENE-P models are used to describe the rheology of fluids in the peripheral and the core regions, respectively. Governing

    更新日期:2020-02-28
  • Capillary flow of sodium and zinc ionomers
    Phys. fluids (IF 2.627) Pub Date : 2020-02-18
    Muaad Zuliki, Tanja Tomkovic, Savvas G. Hatzikiriakos

    The capillary flow properties of several commercial ionomers (sodium and zinc) were studied to assess their processability in terms of instabilities such as wall slip and melt fracture. Using capillary dies of various diameters and lengths to control capillary extrusion pressure, it was found that the viscosity of these polymers exhibits a relatively small dependence on pressure, more importantly at

    更新日期:2020-02-28
  • Series expansion for normal stress differences in large-amplitude oscillatory shear flow from Oldroyd 8-constant framework
    Phys. fluids (IF 2.627) Pub Date : 2020-02-25
    P. Poungthong, A. J. Giacomin, C. Kolitawong

    The Oldroyd 8-constant framework for continuum constitutive theory contains a rich diversity of popular special cases for polymeric liquids. In this paper, we focus on the normal stress difference responses to large-amplitude oscillatory shear (LAOS) flow. The nonlinearity of the polymeric liquids, triggered by LAOS, causes these responses at even multiples of the test frequency. We call responses

    更新日期:2020-02-28
  • Modeling of particle cloud dispersion in compressible gas flows with shock waves
    Phys. fluids (IF 2.627) Pub Date : 2020-02-03
    Guodong Gai, Olivier Thomine, Abdellah Hadjadj, Sergey Kudriakov

    The effect of shock waves on the dispersion characteristics of a particle cloud is investigated both numerically and analytically. A one-dimensional analytical model is developed for the estimation of the cloud topology in the wake of a shock wave, as a function of time, space, and characteristic response time τp of the cloud based on the one-way formalism. The model is compared with the results obtained

    更新日期:2020-02-28
Contents have been reproduced by permission of the publishers.
导出
全部期刊列表>>
全球疫情及响应:BMC Medicine专题征稿
欢迎探索2019年最具下载量的化学论文
新版X-MOL期刊搜索和高级搜索功能介绍
化学材料学全球高引用
ACS材料视界
南方科技大学
x-mol收录
南方科技大学
自然科研论文编辑服务
上海交通大学彭文杰
中国科学院长春应化所于聪-4-8
武汉工程大学
课题组网站
X-MOL
深圳大学二维材料实验室张晗
中山大学化学工程与技术学院
试剂库存
天合科研
down
wechat
bug