Unsteady Flow Of Incompressible Fluid Research Articles

Heat and Mass Transfer in Unsteady MHD Casson Fluid Flow Over a Semi-Infinite Vertical Plate Through Porous Medium with Dissipative and Radiative Effects

Nowadays, Casson fluid and its diverse applications are highly effective across a vast array of industrial, biological and environmental sectors, due to its unique flow properties. This study focuses on the numerical investigation of the heat and mass transfer characteristics of an unsteady incompressible Casson fluid flow over a semi-infinite vertical flat plate by considering free convection effects. The fluid is conducting the electrical current as it moves through the porous medium. The formulation of the governing equation is based on the use of this phenomenon. In the model, the formulated governing equations are converted into non-dimensional form first, and the MHD mathematical model is analyzed using the boundary conditions. The scheme of finite difference method is implemented to solve the model, where concentration profiles are also discussed. Stability and convergence criteria are applied for the accuracy of numerical techniques, and the effects of various parameters on skin friction, rate of heat and mass transfer have been examined significantly. The results indicate that the temperature of the plate increases with the increase in the value of the magnetic parameter for the Casson fluid but the reverse is observed in its limiting case. The present results are compared and checked with previously published results and a remarkable conclusion is given at the end of the study.

Unsteady radiative flow of a viscous incompressible fluid past an accelerated heat transfer isothermal infinite vertical plate with chemical reaction

Unsteady radiative flow of a viscous incompressible fluid past an accelerated heat transfer isothermal infinite vertical plate with chemical reaction

Soret and Dufour effects on an unsteady MHD flow about a permeable rotating vertical cone with variable fluid properties

The objective of the present work is to examine the characteristics of unsteady incompressible magnetohydrodynamic fluid flow around a permeable rotating vertical cone. The effects of thermal radiation, viscous dissipation, and the Soret and Dufour effects are investigated in the analysis of heat and mass transfer. The viscosity of the fluid is considered inversely proportional to the temperature, and the thermal conductivity of the fluid is considered directly proportional to the temper-ature. The governing equations are converted into ordinary differential equations using suitable similarity transformations, which are then solved numerically using bvp4c from MATLAB. Results obtained in this study are in excellent correlation with previously conducted studies. The results demonstrate that the Dufour and Soret effects subsequently reduce the heat transit rate (by –3.3%) and mass transit rate (by –1.2%) of the system. It is also detected that fluids with higher viscosity tend to increase tangential skin friction (+8.9%) and azimuthal skin friction (+8.3%). The heat transit rate of the system is found to be more efficient for fluids with higher viscosity and lower thermal conductivity and Eckert numbers. Further-more, the thickness of the momentum, thermal, and concentration boundary layers significantly reduces while the heat and mass transit rates (+17.8% and +18.3%, respectively) of the system become more efficient for greater values of the un-steadiness parameter.

Exact solutions to vorticity of the fractional nonuniform Poiseuille flows

Abstract Closed-form expressions for the dimensionless velocity, shear stresses, and the flow vorticity fields corresponding to the isothermal unsteady Poiseuille flows of a fractional incompressible viscous fluid over an infinite flat plate are established. The fluid motion induced by a pressure gradient in the flow direction is also influenced by the flat plate that oscillates in its plane. The vorticity field is dependent on two spatial coordinate and time, and it is an arbitrary trigonometric polynomial in the horizontal coordinate. The exact solutions, obtained by generalized separation of variables and Laplace transform technique, are presented in terms of the Wright function and complementary error function of Gauss. Their advantage consists in the fact that the values of the fractional parameter can be chosen so that the predicted material properties by them to be in agreement with the corresponding experimental results. In addition, they describe motions for which the nontrivial shear stresses are influenced by history of the shear rates. It is found that the flow vorticity is stronger near the plate, but it could be attenuated in the case of fractional model.

Series solution of time-fractional mhd viscoelastic model through non-local kernel approach

The study of ramped condition in the context of unsteady incompressible magnetohydrodynamic Casson fluid flow over a moving vertical plate is a complex and important topic in fluid dynamics and heat transfer. This scenario combines several physical phenomena and has practical applications in various engineering and scientific fields. In this study, Casson fluid is considered unsteady under the influence of magnetic field. The fractional mathematical model is proposed by considering the effect of chemical reaction parameter of the flowing fluid. The governing equations are transformed into the dimensionless form and developed fractional models like Caputo-Fabrizio and Atangana-Baleanu Derivative. We used the Laplace transform technique to find the solution of the dimensionless governing equation analytically. The transformed solutions for velocity, energy and momentum balances developed in terms of series. MATHCAD software is being used for numerical computations and the physical attributes of material and fractional parameters are discussed. To analyze their behavior clearly, two-dimensional graphical results are plotted for velocity profile and temperature as well. It has been concluded that the fluid’s velocity are reduced for larger values of the fractional parameter and Prandtl number and is maximum for small values of both parameters. Further, the velocity behavior becomes larger for isothermal condition as compared to ramped conditions.

Optimization of mass and heat flux of MHD viscous fluid flow with constant proportional Caputo derivative by using response surface methodology: Sensitivity analysis

The study of viscous dissipation in the context of unsteady incompressible magnetohydrodynamic viscous fluid flow over a moving plate is a complex and important topic in fluid dynamics and heat transfer. This scenario combines several physical phenomena and has practical applications in various engineering and scientific fields. The fractional mathematical model is proposed by considering the effect of viscous dissipation force of the flowing fluid. For this purpose, fluid is assumed to be lying over a vertical plate that is moving in its own plane. The governing equations are transformed into the dimensionless form and developed fractional model with a new operator Constant Proportional Caputo Derivative. We used the Laplace transform technique to find the solution of the dimensionless governing equation analytically. The transformed solutions for energy and momentum balances developed in terms of series. The validation of the present model comparison graphs is plotted for temperature. The sensitivity of different input parameters on output response are analyzed and displayed the sensitivity results in tabular and graphical form and found that the permeable parameter is most sensitive to skin friction coefficient, and the Eckert number is most sensitive parameter among others to Nusselt Number. The novelty of present work is to develop a correlation between input parameters and output responses by using Response Surface Methodology (RSM). As no such correlation has been developed for optimization of mass and heat flux of MHD viscous fluid flow with Constant Proportional Caputo derivative by using RSM. By using this correlation, we have performed sensitivity analysis for output responses.

The Effect of Variable Heat Flux on Unsteady Laminar MHD Boundary Layer Flow and Heat Transfer Due to a Stretching Sheet

The purpose of this research is to look into the solution technique for obtaining MHD velocity and temperature profiles. In the presence of a changing heat flux, the unsteady laminar boundary layer flow and heat transfer of a viscous incompressible fluid across a stretching sheet are numerically investigated. The unsteadiness is thought to be generated by a sudden increase in the surface temperature and a time-dependent stretching velocity. The flow and heat transfer partial differential equations were numerically solved using an implicit finite difference scheme and a quasi-linearization technique. Both velocity and temperature rise with time and magnetic field, according to the findings. The computed results are compared to previous work that has been published. Variable heat flux (VHF) conditions have also been taken into account.

Impact of chemical reaction, viscous dissipation and thermal radiation on MHD flow past an oscillating plate

This study analyzes the consequences of first-order chemical reactions, radiation, and viscous dissipation on the unsteady magnetohydrodynamic natural convective flow of a viscous incompressible fluid over a vertically positioned semi-boundless oscillating plate with uniform mass diffusion and temperature. An implicit finite-difference technique is employed to solve a set of dimensionless, coupled, nonlinear partial differential equations. The numerical results for fluid velocity, concentration, and temperature at the plate under different dimensionless parameters are graphically displayed. Due to first-order homogeneous chemical reactions, it has been discovered that the velocity rises at the time of a generative reaction and drops during a destructive reaction. A decline in velocity is observed with an increase in the phase angle, radiation parameter, and chemical reaction parameter. Further, it has been revealed that plate oscillation, radiation, chemical reactions, and the magnetic field significantly influence the flow behavior.

Unsteady Casson fluid flow on MHD with an internal heat source

The present paper investigates the heat transfer features of a viscous fluid in an unsteady incompressible Casson fluid flow through a porous medium with an internal heat source under the influence of a magnetic field. A Casson fluid passes through the given porous medium using Darcy model. The study involves simulating the flow using mathematical models based on conservation laws and similarity transformations. The resulting highly nonlinear coupled ordinary differential equations are solved using the Bernoulli wavelet numerical approach. The study utilizes graphical tools to illustrate the flow behaviour under different physical factors, including the effect of the internal heat source. The normalization of the flow behaviour by the magnetic field suggests that it could potentially be used to control various flows. The study finds that various physical parameters which affects the velocity and temperature profiles of the fluid.

Nonlinear Dynamics of Perturbations of a Plane Potential Fluid Flow: Nonlocal Generalization of the Hopf Equation

In this paper, we analytically study the two-dimensional unsteady irrotational flow of an ideal incompressible fluid in a half-plane whose boundary is assumed to be a linear sink. It is shown that the nonlinear evolution of perturbations of the initial uniform flow is described by a one-dimensional integro-differential equation, which can be considered as a nonlocal generalization of the Hopf equation. This equation can be reduced to a system of ordinary differential equations (ODEs) in the cases of spatially localized or spatially periodic perturbations of the velocity field. In the first case, ODEs describe the motion of a system of interacting virtual point vortex-sinks/sources outside the flow domain. In the second case, ODEs describe the evolution of a finite number of harmonics of the velocity field distribution; this is possible due to the revealed property of the new equation that the interaction of initial harmonics does not lead to generation of new ones. The revealed reductions made it possible to effectively study the nonlinear evolution of the system, in particular, to describe the effect of nonlinearity on the relaxation of velocity field perturbations. It is shown that nonlinearity can significantly reduce the relaxation rate by more than 1.5 times.

The Effect of Concentration on the Radiative Flow of Unsteady Magneto hydro – Dynamics (MHD) in a Vertical Channel

The article discusses the effect of concentration on the radiative flow of unsteady Magneto Hydro – Dynamics (MHD) in a porous vertical channel. The approach used in this article is transversely imposed magnetic field on the combination of porosity and viscosity on unsteady incompressible fluid flow and heat transfer. The resulted sets of non – linear coupled differential equation with the governing equations are solved by perturbation technique. The following parameters: Womersely Parameter (AI), Eckert Number (EC), Reynolds Number (Re), Prandlt Number (Pr), Grashof Number (Gr), Schmidt Number (Sc), Chemical Reaction Parameter (Ki) and the Mass Grashof Number (Gc) are used in investigating the nature of the flow due to velocity, temperature and concentration profile. Graphical results are presented and discussed.

Evolution of nonlinear perturbations for a fluid flow with a free boundary. Exact results

The problem of a plane unsteady potential flow of an ideal incompressible fluid bounded by free boundary segments with a constant pressure and by solid walls moving in accordance with a known law is considered. External forces are absent, and capillary forces are neglected. An approach to constructing exact solutions for this type of problem is proposed. The corresponding solutions can be treated as nonlinear perturbations of a certain base flow. As an example of the application of this approach, nonlinear perturbations in a known problem of a fluid flow with a linear velocity field in the region bounded by a straight-line free boundary and parallel approaching or receding solid walls are considered. It is demonstrated that perturbations grow, which leads to variants of the formation of singularities on the free surface of the fluid within a finite time: formation of droplets, bubbles or cusps. A solution describing the collapse of a bubble in a fluid layer bounded by two approaching solid walls has also been found and studied. Thus, a new method of studying nonlinear stability of complicated unsteady fluid flows with combined boundary conditions is proposed and tested.

An extended and improved particle‐spectral method for analysis of unsteady inviscid incompressible flows through a channel of finite length

AbstractThis paper addresses the development of a method to simulate and analyze unsteady flows of incompressible and inviscid fluids in rectangular channels. Mathematically, the flow problem formulates as Euler equations in terms of the stream function and vorticity. The normal velocity and the vorticity are given at the inlet of the channel, and only the normal velocity is specified at the outlet. The particle‐spectral method describes the vorticity field change in a Lagrangian sense by dynamics of marker particles and an Eulerian description of the velocity field using the global Galerkin approximation. The method involves the subdivision of flow domain on rectangular cells; the approximation of vorticity distribution in cells by least‐squares method; Galerkin coefficients calculation using analytical integration on space variables. For time integration, the five‐stage Runge‐Kutta method of the third accuracy order and the sixth one of symplecticity with adaptive step size control uses. The extension of the particle‐spectral approach comprises algorithms for fluid flows qualitative analysis jointly with the time simulation of unsteady flows. This includes the trajectories of marker particles calculation, computing the particle's residence time in the channel, kinetic energy dynamics, and algorithms for analyzing the dynamics and mixing of vortex patches. Test calculations based on reference solutions showed the effectiveness and good accuracy of the particle‐spectral approach. Using the developed method the dynamics of one and two initial vortex patches in the channel were investigated. We found the final state of their long‐time dynamics is time‐periodic or quasi‐periodic movements. The application of qualitative analysis algorithms demonstrates these final states produce a chaotic scattering of fluid particles in the flow‐through zone of the channel.

Simulation of unsteady MHD flow of incompressible fluid between two parallel plates using Laplace-Adomian decomposition method

The aim of this study is to numerically obtain the solution to an unsteady incompressible fluid confined between two parallel plates with constant velocity. The nonlinear partial differential equation governing the flow is first converted to a nonlinear ordinary differential equation using similarity transformation and solved using the combination of Laplace transform and Adomian decomposition method (LADM). The model parameters affecting the flow geometry is analysed and presented in tables and graphs. The method produces an accurate, elegant, computable, and approximately convergent solution which gives great insight but with less mathematical sophistication.

Simulation of unsteady MHD flow of incompressible fluid between two parallel plates using Laplace-Adomian decomposition method

Simulation of unsteady MHD flow of incompressible fluid between two parallel plates using Laplace-Adomian decomposition method

Unsteady Flow of an MHD Tangent Hyperbolic Nanofluid Over a Stretching Sheet

Abstract The recent article addresses the unsteady flow of MHD incompressible tangent hyperbolic fluid with Nanofluid particles in the direction of a stretching surface. Nano-fluid is related to thermo-phoretic and Brownian movement. With proper help through the transformation procedure, the set of non-linear (PDEs) is re-framed into (ODEs). The initiate expressions of momentum, temperature field, and nano-particle concentration are composed into groups of nonlinear equations. That consequential terminology is computed shooting system. The impact of fundamental parameters on the flow field, thermal circulation, and meditation is described. Moreover, the flow field behavior due to the Wall friction, local Nusselt, and Sherwood numbers are examined. This study is significant as this transformation determined the shooting technique’s numerical result and ensured the physical parameters’ behavior graphically. The results show that the velocity field diminishes by escalating the Weissenberg (We) figure and power-law index (n), while thermal and concentration fields remain to detect elevating at similar parameters. Furthermore, the computed result is compared with existing literature and gets accuracy.

NUMERICAL STUDY OF THE INFLUENCE OF TEMPERATURE-DEPENDENT VISCOSITY ON THE UNSTEADY LAMINAR FLOW AND HEAT TRANSFER OF A VISCOUS INCOMPRESSIBLE FLUID DUE TO A ROTATING DISC

In this article, the effect of temperature-dependent viscosity (TVD) on the unsteady laminar flow and heat transfer (HT) of a viscous incompressible fluid due to a rotating disc (RD) has been investigated numerically by exploiting an in-house numerical code. A set of time-dependent, axisymmetric, and non-linear partial differential equations which govern the fluid flows and heat transfer are reduced to non-linear local non-similarity ordinary differential equations by introducing a newly developed group of transformations for different time regimes. Three different solution methods, such as, (i) perturbation solution method for small t, (ii) asymptotic solution method for large t, and (iii) implicit finite difference method for the entire t regime, have been applied to solve the resulting equations treating t as the time-dependent rotating parameter. The local radial skin friction, tangential skin friction and the heat transfer are computed at the surface of the disc for different numerical parameters, such as, Prandtl number, Pr and the viscosity-variation parameter, e. Besides, the key dimensionless quantities such as velocity and temperature profiles, which are inherently linked with the boundary layer thickness, are presented graphically for different values of e while Pr = 0.72. It is found that the dimensionless radial, tangential and axial velocity profiles decrease as e increases, and consequently, the momentum boundary layer thickness is decreased. On the other hand, the non-dimensional temperature profiles are increased owing to the increasing values of e, and this effect eventually leads to a small increment in the thermal boundary layer thickness.

On the Incompressible Fluid Flow over the Prismatic Bodies

In the paper the unsteady incompressible fluid flow over the infinite and finite prismatic bodies is studied. Mathematically this problem is modeled as 3D Navier-Stokes equations (NSE) for the fluid velocity components with the appropriate initial-boundary conditions. The study of the fluid flow over the bodies with the sharp edges is the important problem of Aerodynamics and Hydrodynamics. We admit that near the sharp edges the velocity components are non-smooth. By the methods of mathematical physics the bounded novel exact solutions are obtained for the specific pressure. The profile of the velocity is plotted by means of “Maplesoft”.

INVESTIGATION OF A TWO-DIMENSIONAL UNSTEADY LAMINAR BOUNDARY LAYER OF AN INCOMPRESSIBLE FLUID FLOW

A system of Navier-Stokes equations for two-dimensional unsteady flows of a viscous incompressible fluid in a boundary layer is considered. The physical quantities of the longitudinal and transverse components of velocity, pressure are decomposed into an asymptotic series by degrees of the small parameter ε. The estimation of the individual terms of the equations from the point of order of their magnitude has been preliminarily performed. Output to a recurrent system of partial differential equations of the second order with respect to the first approximation of physical quantities, a system of Prandtl equations is obtained, which is the main one in the study of incompressible fluid flows in the boundary layer, the following approximations are linear partial differential equations of the second order with variable coefficients. Precisely asymptotic solutions of the equation of hydrodynamic boundary layer on a flat plate have been found. Integrate a nonlinear ordinary third-order differential equation with certain current functions distributed by current speeds. The conditions for the separation of the boundary layer and the friction resistance have been established.

Efficient Simulations of Large Scale Convective Heat Transfer Problems

We describe an approach for efficient solution of large scale convective heat transfer problems, formulated as coupled unsteady heat conduction and incompressible fluid flow equations. The original problem is discretized in time using classical implicit methods, while stabilized finite elements are used for space discretization. The algorithm employed for the discretization of the fluid flow problem uses Picard's iterations to solve the arising nonlinear equations. Both problems, heat transfer and Navier-Stokes quations, give rise to large sparse systems of linear equations. The systems are solved using iterative GMRES solver with suitable preconditioning. For the incompressible flow equations we employ a special preconditioner based on algebraic multigrid (AMG) technique. The paper presents algorithmic and implementation details of the solution procedure, which is suitably tuned, especially for ill conditioned systems arising from discretizations of incompressible Navier-Stokes equations. We describe parallel implementation of the solver using MPI and elements of PETSC library. The scalability of the solver is favourably compared with other methods such as direct solvers and standard GMRES method with ILU preconditioning.