Unsteady Fluid Flow Research Articles

Viscous dissipation and radiation absorption effects on unsteady MHD free convective fluid flow past an inclined porous plate with chemical reaction

AbstractThe current scrutinization concentrated on the consequences of viscous dissipation and chemical reaction on unsteady MHD two‐dimensional free convective fluid flow past a semi‐infinite inclined permeable plate with radiation absorption and heat generation. The governing equations are determined analytically by employing the perturbation technique. The impact of various physical estimators on velocity, temperature, concentration, skin friction, and Nusselt number along with Sherwood number were exemplified quantitatively through graphs. It was concluded that velocity declined with the incremental values of Eckert number, but contradictory impact occurred in the case of skin friction. In addition temperature, Nusselt number, as well as velocity, declined with the progressive values of radiation absorption. However, skin friction was accelerated with the augmented values of radiation absorption. Velocity accelerated, with the progressive values of angle of inclination. Concentration declined with the various augmentation values of chemical reaction as well as Schmidt number.

Radiation effect on transient natural convective MHD flow over a fixed cylinder in a permeable medium with heat and mass transport

The thermal radiation impact on the unsteady magnetohydrodynamic flow of a Newtonian fluid past a stationary vertical cylinder with heat and solute transfer has been investigated. The viscous fluid is slightly electrically conductive, and the stationary cylinder is placed in a permeable medium. The linear PDEs that govern the flow is transformed to non-dimensional by suitable non-dimensional quantities, and the standard Laplace transform approach is used to derive the closed-form solutions. The impacts of the flow parameters are discussed through a table and graphs. It is found that the unsteady fluid velocity enhances with a rise in radiation parameter, permeability parameter and time, whereas it falls with reduced magnetic effect. The absolute skin friction value rises with an increase in thermal radiation and porosity parameter but falls with a rise in Schmidt number and transverse magnetic field.

Chemical reaction and Soret effect on an unsteady MHD heat and mass transfer fluid flow along an infinite vertical plate with radiation and heat absorption

In the current investigation, it is anticipated to examine the influence of heat absorption and radiation on an unsteady transient MHD heat and mass transfer natural convective flow of an optically thin non-Grey Newtonian fluid through an abruptly started infinite vertical porous plate with ramped wall temperature and plate velocity in the presence of Soret and chemical reaction of the first order is solved precisely. Using the similarity variables, the governed PDE's are converted into dimensionless governing equations and they are solved numerically by employing the finite element technique. Numerical calculations and graphs are used to illustrate the important features of the solution on fluid flow velocity, heat, and mass transfer characteristics under different quantities of parametric circumstances entering into the problem. Moreover, we computed the physical variables such as the coefficient of drag force, rate of heat, and mass transfer. The findings indicate that when the thermal radiation parameter increases, the thermal boundary layer becomes thinner. To establish the veracity of our present results, we compared them to previously published research and found substantial concordance.

Hydromagnetic mixed convection unsteady radiative Casson fluid flow towards a stagnation‐point with chemical reaction, induced magnetic field, Soret effect, and convective boundary conditions

AbstractThis article presents the two‐dimensional mixed convective MHD unsteady stagnation‐point flow with heat and mass transfer on chemically reactive Casson fluid towards a vertical stretching surface. This fluid flow model is influenced by the induced magnetic field, thermal radiation, viscous dissipation, heat absorption, and Soret effect with convective boundary conditions and solved numerically by shooting technique. The calculations are accomplished by MATLAB bvp4c. The velocity, induced magnetic field, temperature, and concentration distributions are displayed by graphs for pertinent influential parameters. The numerical results for skin friction coefficient, rate of heat, and mass transfer are analyzed via tables for different influential parameters for both assisting and opposing flows. The results reveal that the enhancement of the unsteadiness parameter diminishes velocity and induced magnetic field but it rises temperature and concentration distributions. Moreover, higher values of magnetic Prandtl number enhance Nusselt number and skin friction coefficient, but it has the opposite impact on Sherwood number. We observe that the amplitude is higher in assisting flow compared to opposing flow for skin friction coefficient and Nusselt number whereas opposite trends are noticed for Sherwood number. Our model will be applicable to various magnetohydrodynamic devices and medical sciences.

Unsteady MHD Williamson Fluid Flow with the Effect of Bioconvection over Permeable Stretching Sheet

The unsteady flow of Williamson fluid with the effect of bioconvection in the heat and mass transfer occurring over a stretching sheet is investigated. A uniform magnetic field, thermal radiation, thermal dissipation, and chemical reactions are taken into account as additional effects. The physical problem is formulated in the form of a system of partial differential equations and solved numerically. For this purpose, similarity functions are involved to transmute these equations into corresponding ordinary differential equations. After that, the Runge-Kutta method with shooting technique is employed to evaluate the desired findings with the utilization of a MATLAB script. As a result, the effects of various physical parameters on the velocity, temperature, and nanoparticle concentration profiles as well as on the skin friction coefficient and rate of heat transfer are discussed with the aid of graphs and tables. The parameters of Brownian motion and thermophoresis are responsible for the rise in temperature and bioconvection Rayleigh number diminishes the velocity field. This study on nanofluid bioconvection has been directly applied in the pharmaceutical industry, microfluidic technology, microbial improved oil recovery, modelling oil and gas-bearing sedimentary basins, and many other fields. Further, to check the accuracy and validation of the present results, satisfactory concurrence is observed with the existing literature.

Unsteady oblique stagnation-point flow and heat transfer of fractional Maxwell fluid with convective derivative under modified pressure field

Unsteady oblique stagnation-point flow and heat transfer of fractional Maxwell fluid with convective derivative towards an oscillating tensile plate are discussed in this paper. The fractional operator is introduced to material derivative for the first time to obtain a newly defined constitutive equation of Maxwell fluid. The Fourier's law is modified accordingly. The pressure gradient is innovatively obtained by solving the differential equation, which bases on the momentum equation away from the plate. Furthermore, the numerical solutions are acquired by virtue of the finite difference method combined with L1-algorithm. It turns out to be convergent through constructing numerical example. The influence of related parameters on the velocity and temperature are performed graphically in detail. Results show that the fluid velocity and temperature distributions tend to periodic oscillation near the plate. Both the velocity and the temperature reduce with the augment of fractional derivative parameters, which indicates the velocity and the temperature boundary layer become thinner. The smaller velocity relaxation time parameter leads to enhanced velocity, meaning that the pressure promotes the fluid velocity. It is evident that all the temperature curves have a tendency to increase first and then decrease with the diverse parameters due to the thermal relaxation characteristic.

Numerical analysis of unsteady momentum and heat flow of dusty tangent hyperbolic fluid in three dimensions

This paper explores the impact of MHD and viscous dissipation with joule heating on convective stretching flow of dusty tangent hyperbolic fluid over a sheet in 3D. A time-dependent magnetic field is applied along the z-axis and the sheet being stretched along the xy-plane. The fluid and dust particles motions are coupled only through drag and heat transfer between them. The effect of viscous dissipation with convection is appreciable when the generated kinetic energy becomes appreciable as compared to the amount of heat transferred. A well known bvp4c method has been used to find the fruitful results. Graphs and tables show the facts and figures for physical properties according to different parameters. The main findings are that Increase in power law index, magnetic field, Weissenberg effect, concentration of dust particles, and unsteadiness parameter reduces the flow of fluid and solid granules.

Unsteady natural convection flow due to fractional thermal transport and symmetric heat source/sink

Unsteady natural convection flow of viscous fluids in a circular cylinder, due to a generalized fractional thermal transport is analytically studied. The considered mathematical model is based on a new fractional differential constitutive equation of the thermal flux suitable to describe the thermal memory effects. To develop the mathematical model, the time-fractional Caputo-Fabrizio derivative is used. The generalized constitutive equation becomes equivalent to the classical Fourier's law for the zero value of the fractional order of derivative. Analytical solutions for the fluid temperature and velocity are determined using the Laplace and finite Hankel transforms. The influence of the memory parameter on heat transfer and fluid motion is discussed by numerical simulations and graphical illustrations.

Acoustic scattering in a small centrifugal compressor based on the use of linearized equations in a rotating frame

Numerical solutions of acoustic wave scattering are often used to describe sound propagation through complex geometries. For cases with flow, various forms of the convected equation have been used. A better alternative that includes vortex-sound interaction is instead to use the linearized and harmonic forms of the unsteady fluid flow governing equations. In this paper, a formulation of the linearized equations that include rotational effects, in an acoustic computation using a rotating frame of reference in a stationary geometry, is presented. We demonstrate that rotational effects can be important, e.g., when computing the transmission loss through high-speed compressors. The implementation of the proposed addition to the existing schemes is both simple and numerically inexpensive. The results are expected to have an impact on the research and development related to noise control of high-performance turbo-machinery, e.g., used in automotive or aviation applications at operating conditions that can be represented by steady background flows.

Kinematic Properties of a Twisted Double Planetary Chaotic Mixer: A Three-Dimensional Numerical Investigation.

In this study, a numerical investigation based on the CFD method is carried out to study the unsteady laminar flow of Newtonian fluid with a high viscosity in a three-dimensional simulation of a twisted double planetary mixer, which is composed of two agitating rods inside a moving tank. The considered stirring protocol is a “Continuous sine squared motion” by using the dynamic mesh model and user-defined functions (UDFs)to define the velocity profiles. The chaotic advection is obtained in our active mixers by the temporal modulation of rotational velocities of the moving walls in order to enhance the mixing of the fluid for a low Reynolds number and a high Peclet number. For this goal, we applied the Poincaré section and Lyapunov exponent as reliable mathematic tools for checking mixing quality by tracking a number of massless particles inside the fluid domain. Additionally, we investigated the development of fluid kinematics proprieties, such as vorticity, helicity, strain rate and elongation rate, at various time periods in order to view the impact of temporal modulation on the flow properties. The results of the mentioned simulation showed that it is possible to obtain a chaotic advection after a relatively short time, which can deeply enhance mixing fluid efficiency.

Mathematical analysis of heat and fluid flow in a square cavity

Theoretical analysis of heat transfer plays a vital role in updating the quality of heat exchanger products. Experiments cost more compared to computational costs. In this direction, this work is concerned with the unsteady and incompressible fluid flow with a rod inside a square cavity. The disturbance in the flow is induced by the motion of the top and bottom walls of the cavity. The maximum fluid flow will arise, which will help in reducing the temperature of the heated wall or rod in any physical situation. A single wall is considered to be heated, which produces heat in the neighboring fluid layers. A rod is placed to reduce the motion of the heated fluid coming from the heated wall at a high-temperature. The transmission of thermal energy along with fluid flow is carried out using the energy equation and the Navier–Stokes equation of motion, respectively. These equations are transformed to dimensionless form by appropriate parametrization and solved using the finite element method for different parameters such as Rayleigh number and Prandtl number, temperature and velocity fields and are presented graphically

Unsteady MHD fluid flow over an inclined plate, inclined magnetic field and variable temperature with Hall and Ion-slip current

Unsteady MHD fluid flow over an inclined plate, inclined magnetic field and variable temperature with Hall and Ion-slip current

Irreversibility analysis in time-dependent Darcy–Forchheimer flow of viscous fluid with diffusion-thermo and thermo-diffusion effects

Abstract In this article, we analyze the entropy analysis in unsteady hydromagnetic flow of a viscous fluid over a stretching surface. The energy attribute is scrutinized through dissipation, heat source/sink, and radiation. Furthermore, diffusion-thermo and thermo-diffusion behaviors are analyzed. The physical description of the entropy rate is discussed through the second law of thermodynamics. Additionally, a binary chemical reaction is considered. Partial differential equations are transformed into ordinary ones by adequate variables. Here, we used an optimal homotopy analysis method (OHAM) to develop a convergent solution. The influence of flow variables on velocity, Bejan number, thermal field, concentration, and entropy rate is examined through graphs. The physical performance of drag force, Sherwood number, and temperature gradient versus influential variables is studied. A similar effect holds for velocity through variation of porosity and magnetic variables. An increment in thermal field and entropy rate is noted through radiation. A reverse trend holds for the Bejan number and thermal field through a magnetic variable. An augmentation in the Soret number enhances the concentration. An amplification in drag force is noted through the Forchheimer number. Higher estimation of radiation corresponds to a rise in the heat transfer rate.

Impact of thermal radiation on two-dimensional unsteady third-grade fluid flow over a permeable stretching Riga plate

In many fields, there are various applications of non-Newtonian fluids. Various complicated fluids (polymer melts, clay coatings and oil) belong to the category of non-Newtonian fluids. The third-grade fluid is one of the most important non-Newtonian fluid models. This paper has the primary object of heat transfer mechanism and boundary layer third-grade fluid flow under the effects of thermal radiation. The time-dependent two-dimensional flow is considered to flow above a permeable stretchable vertical Riga plate. For numerical solutions, the setup of ordinary differential equations (ODEs) is acquired by converting nonlinear governing equations through relevant similarity transformations. The nonlinear setup of ODEs is numerically solved with the aid of a suitable software such as MATLAB via its bvp4c technology. Graphs are sketched to discuss the various flow parameters’ significance for the expression of velocity and temperature fields. Tabulated values of surface drag force and heat transfer rate corresponding to the numerous pertinent parameters are described. The current analysis of the concerned flow mechanism concludes that the fluid parameters descend the temperature distribution but amplify the profile of the fluid velocity. The radiation parameter escalates the temperature field.

Multiple Slip effects on unsteady MHD Casson nano fluid flow over a porous stretching sheet

Multiple Slip effects on unsteady MHD Casson nano fluid flow over a porous stretching sheet

Unsteady Fluid Flows in the Slab Mold Using Anticlogging Nozzles

The characterization of the fluid flow of liquid steel in a slab mold, using two nozzle designs under unclogged and clogged conditions, is performed using physical and mathematical simulations. Nozzle A, with an expanding and contracting geometry, yields larger sub-meniscus experimental velocities than nozzle B, with internal flow deflectors. The numerical predictions indicate quick time-changing velocity profiles in the submeniscus region between the mold’s narrow face and the nozzles. The flow deflectors in nozzle B have two effects; the high dissipation rate of kinetic energy in the upper-half length induces lower velocities in the ports than nozzle A. The neutralization of the biased flow caused by the sliding gate allows a balanced fluid through the ports. According to the results, nozzle A yields velocity profiles in the sub-meniscus region with larger standard deviations than nozzle B, leading to an unstable bath surface. The clogged nozzles produced biased-asymmetrical flow patterns in the mold, finding approximated matchings between numerical predictions and experimental measurements. The internal protrusions of the deposits lead to covariance losses of the bath surface wave heights. The use of internal deflectors helped to decrease the amount of clog material in nozzle B.

Suction effect on MHD flow of Brinkman-type fluid with heat absorption and first-order chemical reaction

Suction/injection is a mechanical effect and used to control the energy losses in the boundary layer region by reducing the drag on the surface. In this study, unsteady MHD flow of Brinkman-type fluid with suction/injection, heat absorption, and chemical reaction is investigated and an analytical solution is established. The corresponding results for temperature, concentration, and velocity fields are obtained with the help of the Laplace transformation method analytically. The physical effects of thermal and mass Grashoff number, Prandtl number, Schmidt number, heat absorption parameter, first-order chemical reaction parameter, suction/injection, Brinkman parameter, and magnetic parameter have been discussed graphically. Finally, it is observed that in the presence of suction effect, fluid’s velocity decreases gradually by increasing the value of suction parameter while show an increasing trend for the increasing value of the injection parameter.

Unsteady MHD Thin Film Flow of a Second-Grade Fluid past a Tilted Plate under the Impact of Thermal Radiation and Chemical Reaction

This paper explores the impact of chemical reaction and thermal radiation on time-dependent hydromagnetic thin-film flow of a second-grade fluid across an inclined flat plate embedded in a porous medium. The thermal radiation based on the Rosseland approximation is incorporated in the energy equation. Uniform applied magnetic field and first-order homogenous chemical reaction are included in the momentum and concentration equations, respectively. The novel mathematical flow model is constructed by using a set of partial differential equations (PDEs). The PDEs are then transformed into an equivalent set of ordinary differential equations (ODEs) and solved by applying the Laplace transform method. However, the time domain solutions are obtained by using the INVLAP subroutine of MATLAB. Physical parameters influencing thin-film velocity, temperature, and concentration are illustrated graphically, while those affecting skin friction, heat, and mass transfer rates are presented in a tabular form. It is found that thin-film velocity and temperature boost with increasing values of thermal radiation, but thin-film velocity decreases with increasing values of chemical reaction and magnetic field. The current investigation is to enhance heat and mass transfer in the design of mechanical systems involving the thin film flow of second-grade fluids over an inclined flat plate after applying thermal radiation and chemical reaction.

Casson Fluid Convective Flow in an Accelerated Microchannel with Thermal Radiation using the Caputo Fractional Derivative

The effect of the Caputo fractional derivative in unsteady boundary layer Casson fluid flow in an accelerated microchannel is investigated. In the presence of thermal radiation, the partial differential equations that governed the problem are studied. Using appropriate dimensionless variables, fractional partial differential equations are translated into dimensionless governing equations. The equations are then transformed into linear ordinary differential equations and solved analytically using the Laplace transform technique. These modified equations are then solved using the proper method, and the result is obtained in the form of velocity and temperature profiles using the Zakian’s explicit formula approach. The influence of essential physical parameters on velocity and temperature profiles is investigated using graphical diagrams created with Mathcad software. It is found that the velocity and temperature profile increase as fractional parameter, and thermal radiation parameter increase. As Prandtl number increase, both profiles are decreasing. This result is crucial for understanding the fractional system of Casson fluid in microchannel.

Study unsteady flow of synovial fluid in the elastic porosity of layers using double ZZ transformation

The elastic deformation of the human synovial joint in the standing and swing phases is presented in this paper, as well as the relationship between elastic muscle fibers and layer porosity using a mathematical model and analyzing the results with the appropriate boundary condition for the types of lubrication. During the gait cycle, elastic muscle fibers have a large impact on the magnetic field and the film (thinning of the thickness) of layers. The impact of elastic muscle fibers is to increase the hydrodynamic pressure and carry the load. We employed the double ZZ transformation as a strong tool to acquire a solution to the hydrodynamic pressure and bearing loads directly without finding the general solution of a differential equation.