Flow Past Research Articles

Effects of Soret, Dufour, Variable Viscosity and Variable Thermal Conductivity on Unsteady Free Convective Flow Past a Vertical Cone

Effects of Soret, Dufour, Variable Viscosity and Variable Thermal Conductivity on Unsteady Free Convective Flow Past a Vertical Cone

A Novel Approach on Unsteady MHD Radiative Flow Past an Impulsively Started Isothermal Semi-infinite Vertical Plate with Uniform Mass Flux in a Rotating System

Implicit finite difference scheme has been employed to scrutinize an unsteady MHD flow past an impulsively started semi-infinite isothermal vertical plate in the presence of thermal radiation, rotation and uniform mass flux. Stability analysis is carried out using Von-Neumann technique. The numerical results for the dimensionless velocity profile, temperature profile, concentration profile are obtained by varying the representative values of the magnetic parameter M, rotation parameter, radiation parameter R, Schmidt number Sc, thermal Grashoff number Grand mass Grashoff number Gc. It is observed that rotation retards the primary and secondary velocity profiles, while local and average skin frictions are augmented by increasing the rotation parameter.

CFD Simulation of Flow Past Wing Body Junction: A 3-D Approach

CFD Simulation of Flow Past Wing Body Junction: A 3-D Approach

Influence of Natural Convective Flow Past an Oscillating Semi-Infinite Vertical Plate with Variable Mass Diffusion under First Order Chemical Reaction

The aim of numerical works is to inspect the effect of free convective viscous incompressible displacement, past an oscillating semi-infinite vertical plate along with variable mass diffusion including first order chemical Reaction. The governing equations in the current study were solved by the implicit finite difference scheme. The fluid velocity and transient temperature for different thermal physical Parameters such as the chemical Reaction parameter, Prandtl number, Schmidt number, Sherwood number, thermal Grash of number, and mass Grashof number were studied. The examined associated with the actual solution in the literary works and they entered a good agreement. It was definitely altogether due to the influence of first -order chemical reaction, the velocity increasing during the generative reaction and decreases at the destructive reaction.

A Comparative Study on Turbulence Models for Simulation of Flow Past NACA 0015 Airfoil Using OpenFOAM

An implementation of C++ language open source code software, OpenFOAM, for simulation of flow past NACA 0015 airfoil was performed to access a suitable turbulence model. Three various turbulence models were selected which comprised of Spalart-Allmaras model, RNG k-e model and Menter SST k-ω model, respectively. The SIMPLE algorithm and Upwind method was used to solve the governing equation to achieve flow solutions of computational fluid dynamic (CFD) models. The flow simulation obtained lift coefficient (C L ) and drag coefficient (C D ) to compare with the wind tunnel experiment data at Reynolds number (Re) of 160,000 and 360,000 with the large range airfoil angle of attack (AOA) from 0 to 20 degree. The suitable CFD model was the Menter SST k-ω model which obtained an average error of C L and C D less than 10.96% and 22.21%, respectively.

Soret and Dufour Effects on Steady Free Convection and Mass Transfer Flow Past a Semi-infinite Flat Plate with Viscous Dissipation

The Soret and Dufour effects on a steady free convection and mass transfer flow past a semi infinite flat plate with viscous dissipation in a porous medium have been studied numerically. The equation governing the flow of heat and mass transfer have been solved by Runge Kutta Gill method with shooting technique. The flow characteristics have been studied for different values of Pr, Gb, Sc, Sr and Du.

Unsteady Hydromagnetic Natural Convection Flow Past an Oscillating Vertical Surface with Hall Effect and Convective Boundary Condition

The aim of this paper is to analyze the effect of Hall current on unsteady MHD free convection flow of a viscous, incompressible and electrically conducting fluid past an oscillating vertical plate with convective boundary condition. The fluid flow is due to both the oscillation and the convective heating of the plate. The resulting governing equations are nondimensionalized and solved analytically using the Laplace transform technique. Numerical results for axial and transverse velocities and temperature as well as the skin-friction coefficient and Nusselt number are shown graphically for various values of pertinent flow parameters.

Unsteady MHD Free Convective Flow Past an Inclined Parabolic Accelerated Plate with Hall Current, Radiation Effects and Variable Temperature in a Porous Medium

We analyze the effects of hall current and radiation on unsteady hydromagnetic free convection flow of a viscous incompressible electrically conducting fluid past an inclined parabolic accelerated plate in a porous medium by applying a transverse magnetic field which makes an angle α to the inclined plate.The fluid is assumed to be viscous, incompressible and electrically conducting with a strong magnetic field. Using the modified Ohm’s law and the Bossinesq approximation the governing equations of the problem are reduced to local non-similarity boundary layer equations using suitable transformation.The dimensionless governing equations of flow field are solved numerically by Crank-Nicolson finite difference method for different values of governing flow parameters. The velocity and temperature profiles are shown through graphs.

Numerical Treatment of Casson Fluid Free Convective Flow Past An Infinite Vertical Plate Filled in Magnetic Field in Presence Of Thermal Radiation: A Finite Element Technique

The combined effects of hall current, thermal radiation on an unsteady MHD free convection casson fluid flow of a viscous, incompressible and electrically conducting fluid past an infinite vertical plate are investigated in presence of heat transfer. Numerical solutions of the non-linear coupled governing equations is obtained by finite element technique. The expressions for primary fluid velocity, secondary fluid velocity and fluid temperature, skin friction due to primary and secondary velocity fields and rate of heat transfer coefficient due to temperature at the plate are obtained and discussed with the help of different material parameters like Grashof number for heat transfer, Casson fluid parameter, Magnetic field parameter, hall parameter, thermal radiation parameter, Prandtl number. Finally, it is seen that the numerical results of the present study conform very well to those of previous studies reported in available scientific literatures.

Second Law Analysis of Flow, Heat and Mass Transfer Past a Nonlinearly Stretching Permeable Wedge with Temperature Jump and Chemical Reaction

Abstract Second law analysis (entropy generation) for the steady two-dimensional laminar forced convection flow, heat and mass transfer of an incompressible viscous fluid past a nonlinearly stretching porous (permeable) wedge is numerically studied. The effects of viscous dissipation, temperature jump, and first-order chemical reaction on the flow over the wedge are also considered. The governing boundary layer equations for mass, momentum, energy and concentration are transformed using suitable similarity transformations to three nonlinear ordinary differential equations (ODEs). Then, the ODEs are solved by using a Keller’s box algorithm. The effects of various controlling parameters such as wedge angle parameter, velocity ratio parameter, suction/injection parameter, Prandtl number, Eckert number, temperature jump parameter, Schmidt number, and reaction rate parameter on dimensionless velocity, temperature, concentration, entropy generation number, and Bejan number are shown in graphs and analyzed. The results reveal that the entropy generation number increases with the increase of wedge angle parameter, while it decreases with the increase of velocity ratio parameter. Also, in order to validate the obtained numerical results of the present work, comparisons are made with the available results in the literature as special cases, and the results are found to be in a very good agreement.

On Diffusion of Chemically Reactive Species in a Convective Flow Past an Inclined Plate with Variable Surface Temperature and Variable Mass Diffusion

A numerical solution of a transient natural convection flow past a semi-infinite inclined plate under the combined buoyancy effects of heat and mass transfer along with chemical reaction is presented herewith. The governing boundary layer equations for the above flow problem for a first order homogeneous chemical reaction are set up and non-dimensionalised. An implicit finite difference method is employed to solve the unsteady, nonlinear, integro and coupled partial differential equation. Numerical results are presented for various parameters occurring in the problem. The unsteady velocity, temperature and concentration profiles, local and average skin friction, Nusselt number and Sherwood number are studied for both a generative and destructive reaction.

Thermal Radiation and Heat Transfer Effects on MHD Micro polar Fluid Flow Past a Vertical Plate with Chemical Reaction

Thermal Radiation and Heat Transfer Effects on MHD Micro polar Fluid Flow Past a Vertical Plate with Chemical Reaction

Effect of Aligned Magnetic Field on Casson Fluid Flow Past a Vertical Oscillating Plate in Porous Medium

Effect of Aligned Magnetic Field on Casson Fluid Flow Past a Vertical Oscillating Plate in Porous Medium

Unsteady Visco-elastic Boundary Layer Flow Past a Stretching Plate and Heat Transfer

Unsteady Visco-elastic Boundary Layer Flow Past a Stretching Plate and Heat Transfer

An Exact Analysis of Unsteady MHD Free Convective Chemically Reacting Elasto-Viscous Fluid Flow Past an Impulsively Started Infinite Vertical Plate Through Porous Medium in the Presence of Radiation Absorption

In this paper, an exact analysis is carried out for the Laplace transform solution of unsteady MHD chemically reacting elasto-viscous fluid past an infinite vertical plate through porous medium in the presence of radiation absorption and transverse applied magnetic field. The governing equations describing the flow pattern are transformed to a system of linear partial differential equations using appropriate non-dimensional quantities. The resulting transformed equations are solved analytically by using Laplace transform technique and exact solutions for velocity, temperature and concentration as well as Nusselt number and Sherwood number are obtained in terms of exponential and complementary error functions. Behaviour of emerging parameters like elasto-viscous, heat absorption, radiation absorption, magnetic field, Schmidt number, chemical reaction, thermal Grashof number, mass Grashof number, Prandtl number and time is presented graphically and discussed in detail. It was found that increasing radiation absorption parameter, velocity is decreasing for elasto-viscous fluid, but the reverse effect is found for viscous fluid in case of cooling of the plate. An increase in heat absorption, Schmidt number and chemical reaction lead to rise in the Sherwood number and Nusselt number while a reverse effect is noticed in the flow transport.

Disturbance of a Bow Shock Wave and of Flow Behind It in the Case of Flow Past Blunt Bodies in Polyatomic Gases

A review has been presented of the results of experimental investigations, on a ballistic unit of the Physical-Technical Institute, into the distortion of a bow shock wave and of flow behind the body in CCl2F2 and CF4 polyatomic gases. The latest experimental works at the Physical-Technical Institute and abroad have also been reviewed. The distortion of the bow shock wave under the same conditions is identically manifested in the case of flow past a segmental body and past a sphere alike, although for the sphere, flow separation occurs farther downstream of the bow shock. In the case of flow past a cylinder the initial distribution of the flow is observed in the compression zone behind the bow shock wave.

On the solution variability reduction of Stochastic Dual Dynamic Programming applied to energy planning

In the hydrothermal energy operation planning of Brazil and other hydro-dependent countries, Stochastic Dual Dynamic Programming (SDDP) computes a risk-averse optimal policy that often considers river-inflow autoregressive models. In practical applications, these models induce an undesirable variability of primal (thermal generation) and dual (marginal cost and spot price) solutions that are highly sensitive to changes in current inflow conditions. This work proposes two differing approaches to stabilize SDDP solutions to the energy operation planning problem: the first approach regularizes primal variables by considering an additional penalty on thermal dispatch revisions over time, and the second approach indirectly reduces thermal generation and marginal cost variability by disregarding past inflow information in the cost-to-go function and compensates with an increase in risk aversion. For comparison purposes, we assess solution quality with a set of proposed indexes summarizing each important aspect of a hydrothermal operation planning policy. In conclusion, we show that it is possible to obtain high-quality solutions in comparison to current benchmarks with significantly reduced variability.

Effect of Reynolds Numbers on Flow Past a Square Cylinder in Presence of Multiple Control Cylinders at Various Gap Spacings

In this paper, the numerical investigations for drag reduction and vortex shedding suppression behind a square cylinder are carried out in presence of small control cylinders placed both at upstream and downstream locations of main cylinder. The numerical computations are performed in the ranges of \(80 \le Re \le 200\) and \(0.5 \le g \le 6\), (where Re is the Reynolds number and g is the gap spacing between the control cylinders and main square cylinder, respectively) using a single relaxation time lattice Boltzmann method (SRT-LBM). Firstly, the present code is validated for flow past a single square cylinder at different Reynolds numbers. The effects of Re and g are investigated in terms of vortex shedding frequency, time-history analysis of drag and lift coefficients, energy spectra analysis of lift coefficient, vorticity contours visualization and forces exerted on the cylinder. Three different types of flow patterns are observed at different combinations of Reynolds numbers and gap spacings. The maximum reduction in the mean drag force and root-mean-square value of lift coefficient is found. Furthermore, the applications of SRT-LBM for suppression of vortex shedding and reduction in the drag force are also discussed.

Unsteady Hydromagnetic Natural Convection Flow Past a Vertical Plate with Time-Dependent Free Stream through a Porous Medium in the Presence of Hall Current, Rotation, and Heat Absorption

AbstractAn investigation of the unsteady hydromagnetic natural convection flow of a viscous, incompressible, electrically conducting, and heat-absorbing fluid past an infinite vertical plate through a fluid-saturated porous medium with a time-dependent free stream in a rotating system with Hall effects is carried out. An exact solution of the governing equations is obtained using the Laplace transform technique. Two cases of interest are discussed, viz, (1) the impulsive movement of the free stream and (2) the accelerated movement of the free stream. Expressions for the shear stresses at the plate as a result of the primary and secondary flows and the rate of heat transfer at the plate are derived. Asymptotic behavior of the solution is analyzed for both small and large values of time t to highlight the transient approach to the steady-state flow and to gain some physical insight into the flow pattern. A reverse flow exists in the secondary flow direction because of the presence of the thermal buoyancy fo...

Soret and Dufour Effects on MHD Free Convective Flow Past a Vertical Porous Plate in the Presence of Heat Generation

An MHD fluid flow is examined over a vertical plate in the presence of Dufour and Soret effects. The resulting momentum, energy and concentration equations are then made similar by introducing the usual similarity transformations. These similar equations are then solved numerically using the Runge-Kutta fourth order method with shooting technique. The effects of various parameters on the dimensionless velocity, temperature and concentration profiles as well as the local values of the skin-friction coefficient, the Nusselt number and Sherwood number are displayed graphically and in a tabular form. A comparison with previously published work is obtained and an excellent agreement is found.