Unsteady Flow Of Viscous Fluid Research Articles

Numerical Assessment of the Resistance of a Solar Catamaran in Shallow Water

In this paper, a numerical assessment of the effect of shallow water on the total resistance of the solar catamaran SolarCat is carried out using computational fluid dynamics within the software package STAR–CCM+. The unsteady viscous fluid flow was modelled based on the Reynolds-averaged Navier–Stokes (RANS) equations with the application of the k−ω SST (k−ω Shear Stress Transport) turbulence model. The RANS equations were discretized by the finite volume method, and the position of the free surface is determined by the volume of fluid method. In shallow water conditions, a mesh morphing algorithm is applied. Numerical simulations were carried out for the deep water and limited depths corresponding to h/T=7.6, h/T=4, and h/T=2 at two speeds. The verification study was carried out and the total numerical uncertainty was calculated for the total resistance and sinkage of the catamaran. A detailed analysis of the flow around the catamaran was carried out.

Study of Entropy Generation with Multi-Slip Effects in MHD Unsteady Flow of Viscous Fluid Past an Exponentially Stretching Surface

The current study aims to probe the impacts of entropy in a hydromagnetic unsteady slip flow of viscous fluid past an exponentially stretching sheet. Appurtenant similarity variables are employed to transmute the governing partial differential equations into a system of non-linear differential equations, which are analytically solved by utilizing the homotopy analysis method (HAM). Moreover, a shooting technique with fourth–fifth order Runge–Kutta method is deployed to numerically solve the problem. The impact of the physical parameters that influence the flow and heat transmission phenomena are sketched, tabulated and discussed briefly. Additionally, the impact of these parameters on entropy generation is thoroughly discussed by plotting graphs of the local entropy generation number and the Bejan number.

Fractional Analysis of Viscous Fluid Flow with Heat and Mass Transfer over a Flexible Rotating Disk

An unsteady viscous fluid flow with Dufour and Soret effect, which results in heat and mass transfer due to upward and downward motion of flexible rotating disk, has been studied. The upward or downward motion of non rotating disk results in two dimensional flow, while the vertical action and rotation of the disk results in three dimensional flow. By using an appropriate transformation the governing equations are transformed into the system of ordinary differential equations. The system of ordinary differential equations is further converted into first order differential equation by selecting suitable variables. Then, we generalize the model by using the Caputo derivative. The numerical result for the fractional model is presented and validated with Runge Kutta order 4 method for classical case. The compared results are presented in Table and Figures. It is concluded that the fractional model is more realistic than that of classical one, because it simulates the fluid behavior at each fractional value rather than the integral values.

A reliable algorithm for time-fractional Navier-Stokes equations via Laplace transform

AbstractIn this paper, numerical solution of fractional order Navier-Stokes equations in unsteady viscous fluid flow is found using q-homotopy analysis transform scheme. Fractional derivative is considered in Caputo sense. The proposed technique is a blend of q-homotopy analysis scheme and transform of Laplace. It executes well in efficiency and providesh-curves that show convergence range of series solution.

Irreversibility analysis in unsteady flow over a vertical plate with arbitrary wall shear stress and ramped wall temperature

Abstract The present paper aims to report irreversibility analysis in unsteady flow of viscous fluid over a vertical flat plate with ramped wall temperature and arbitrary wall shear stress in the presence of thermal radiation. The equations which governing the problem are solved by the method of Laplace transform. The expression for Bejan number and volumetric entropy generation rate are calculated. The effects of different embedded parameters on the Bejan number and the entropy generation number are elaborated by graphs. It is noted that entropy production in thermal system can be minimized by decreasing thermal radiation. It is also observed that heat transfer increases the entropy of the system.

Modeling of unsteady flow of viscous fluid in the channel of complex geometry

The article concerns an issue of exploring the mechanism of wave influence on the process of filtration. To describe a filtration flow, the porous medium is represented as a capillary, the radius of which varies sinusoidally. In this article we are presenting the results of numerical modeling of pulsating liquid flow in a sinusoidally-shaped channel. Numerical research was conducted with the help of the program complex FlowVision. As a result of series of calculations we received fields of velocities and pressure in the axial section of flowing channel. It was found that it is the flow in narrow isthmuses between the pores that contributes to the pressure difference the most. We revealed the signs of steady-state liquid flow in the channel when imposing fluctuations of pressure in the absence of pressure gradient. The conditions of formation of such flow are revealed.

Unsteady Viscous Fluid Flow with Porous Medium in the Presence of Radiation and Chemical Reaction

In this paper we consider the problem of unsteady, laminar, boundary layer flow of a viscous, incompressible, electrically conducting fluid along a semi-infinite vertical plate in the presence of a porous medium with radiation and chemical reactions. Using perturbation techniques the expressions for the velocity distribution, temperature distribution, concentration distribution, shear stress, Nusselt number, and Sherwood number are obtained. The velocity increases with an increase in K, Gr, and Gm.

A general formula for the drag on a sphere placed in a creeping unsteady micropolar fluid flow

In the present work, we investigate the creeping unsteady motion of an infinite micropolar fluid flow past a fixed sphere. The technique of Laplace transform is used. The drag formula is obtained in the physical domain analytically by using the complex inversion formula of the Laplace transform. The well known formula of Basset for the drag on a sphere placed in an unsteady viscous fluid flow and that of Ramkissoon and Majumdar for steady motion in the case of micropolar fluids are recovered as special cases. The obtained formula is employed to calculate the drag force for some micropolar fluid flows. Numerical results are obtained and represented graphically.

Unsteady flow of viscous fluid over the vacillate stretching cylinder

SUMMARYIn this paper, we consider the unsteady boundary layer flow of an incompressible viscous fluid produced by periodic motion of an elastic cylinder. The number of independent variables involved in the governing partial differential equations is reduced by using the similarity transformation. The transformed equations are then solved numerically with the help of a finite difference scheme by altering the semi‐infinite domain to a finite domain. The numerical results are compared with a previously published work and a good agreement is achieved. The imperative parameters rising in the governing equations because of the effects of oscillations and the curvature are St (Strouhal number), Re (Reynolds number), and ϵ (amplitude of oscillations). The effects of these parameters on the vacillating velocity and the skin friction are discussed through graphs and tables. The large values of Re correspond to small curvature, so for large Reynolds number the solution approaches to that of the stretching flat plate case. Copyright © 2011 John Wiley & Sons, Ltd.

Numerical Analysis of Heaving Flexible Airfoils in aViscous Flow

A numerical model for two-dimensional unsteady viscous fluid flow around flexible bodies is used to analyze the effectofchordwise flexibilityonheavingairfoils.Flexibleairfoilsprovedtobemoreefficientthantherigidones.Both the output power and the input power increase in the flexible cases. The gain in efficiency is realized as a result of the output power increasing more than the input power. The density of the airfoils was shown to be a key factor in determining efficiency and power. In the parameter range analyzed, heavier airfoils are shown to generate less output power and to require proportionately less input power. Thus, heavier airfoils are more efficient than lighter airfoils. In the numerical model the bodies are represented by a distributed body force in the Navier–Stokes equations. The main advantage of this method is that the computations can be effected on a Cartesian grid, without having to fit the grid to the body surface. This approach is particularly useful when applied to the case of multiple bodies moving relative to each other, as well as flexible bodies, in which case the surface of the object changes dynamically.

Unsteady viscous fluid flow between rotating parallel walls with allowance for thermal slip along one of them

Unsteady viscous fluid flow between rotating parallel walls with allowance for thermal slip along one of them

Eigenvalues of the time—dependent fluid flow problem I

The direct and inverse boundary value problems for the linear unsteady viscous fluid flow through a closed conduit of a circular annular cross‐section Ω with arbitrary time‐dependent pressure gradient under the third boundary conditions have been investigated.

Drag of a sphere in an unsteady flow of viscous fluid at small reynolds numbers

An unsteady flow of viscous incompressible fluid past a sphere is investigated. The values of the inertial and unsteady terms in the Navier-Stokes equations are characterized by translational (R) and vibrational (Rk) Reynolds numbers, which are assumed small. The solution is constructed in the form of an expansion with respect to max(R, R k 1/2 ) by the method of matched asymptotic expansions. A correction to the Stokes force, correct to o[max(R, R k 1/2 )], is calculated. It is shown that the result depends strongly on the ratio R/R k 1/2 and goes over into the well-known equations for the cases R → 0, Rk→ 0.

On the unsteady flow of viscous fluid between two plates

A solution is found for Navier-Stokes equations for the unsteady laminar flow of a viscous incompressible fluid between two horizontal parallel plates, the upper one is moving with an arbitrary velocityU(t) and the other at rest, under the action of an arbitrary pressure gradient.

Shedding of vortices behind a circular cylinder

The process of shedding of vortices from a circular cylinder is discussed by computing an unsteady viscous fluid flow at Reynolds number 200 under natural boundary conditions with a fine mesh near the surface of the cylinder. The phenomena of shedding of vortices is described by drawing streamlines patterns and the equivorticity lines at different times. The variations of the vorticity distribution, the pressure distribution and the drag coefficient at different times are shown by graphs. The Strouhal number for the shedding process is calculated and compared with the known results.

Unsteady viscous fluid flow in cylindrical pipes

Unsteady viscous fluid flow in cylindrical pipes