Values Of Flow Parameters Research Articles

A Study of Chemically Reactive Species and Thermal Radiation Effects on an Unsteady MHD Free Convection Flow Through a Porous Medium Past a Flat Plate with Ramped Wall Temperature

An investigation of the effects of a chemical reaction and thermal radiation on unsteady MHD free convection heat and mass transfer flow of an electrically conducting, viscous, incompressible fluid past a vertical infinite flat plate embedded in a porous medium is carried out. The flow is induced by a general time-dependent movement of the vertical plate, and the cases of ramped temperature and isothermal plates are studied. An exact solution of the governing equations is obtained in closed form by the Laplace Transform technique. Some applications of practical interest for different types of plate motions are discussed. The numerical values of fluid velocity, temperature and species concentration are displayed graphically whereas the numerical values of skin friction, Nusselt number and Sherwood number are presented in a tabular form for various values of pertinent flow parameters for both ramped temperature and isothermal plates.

HEAT TRANSFER TO MHD OSCILLATORY DUSTY VISCO-ELASTIC FLUID FLOW IN AN INCLINED CHANNEL FILLED WITH A POROUS MEDIUM

An analysis of the unsteady MHD oscillatory flow of an incompressible, conducting, optically thin, dusty visco-elastic fluid through an inclined channel filled with saturated porous medium in presence of heat sink parameter and thermal radiation has been considered. The governing nonlinear partial differential equations are nondimensioalized and are solved analytically by using perturbation technique. The expressions for velocity field, temperature field, skin friction, heat flux in terms of Nusselt number, flow flux for fluid and dust particles are obtained within the channel and are discussed graphically for various values of flow parameters involved in the problem.

Nusselt number and friction factor correlations for forced convective type counter flow solar air heater having discrete multi V shaped and staggered rib roughness on both sides of the absorber plate

In this work, the results of an experimental study on heat transfer and friction factor in a counter flow double pass solar air heater (DPSAH) duct with discrete multi V-shaped and staggered rib roughness on two broad surfaces of the heated plate have been investigated. The investigation covers a wide range of Reynolds number (Re) from 2000 to 20,000, relative staggered rib pitch (p′/p) from 0.2 to 0.8, relative staggered rib size (r/e) from 1 to 4 and relative roughness width (W/w) from 5 to 8. The optimum values of flow and geometrical parameters of roughness have been attained and explained in detail. For the Nusselt number (Nu), the maximum increase of 4.52 times to the corresponding value of smooth double pass duct has been achieved, however it has also been seen that the friction factor (f) enhanced by 3.13 folds as compared to smooth one. The rib parameters corresponding to maximum increase in Nu and f are r/e=3.5, p′/p=0.6 and W/w=7. Further, correlations for Nu and f have also been developed on the basis of experimental data.

Fundamental diagrams of pedestrian flow characteristics: A review

IntroductionThe dimensionality of pedestrian infrastructure facilities have a great influence on pedestrian movements and a considerable impact on natural environment of the facility. Understanding the pedestrian movements are crucial to estimate the capacity of the system accurately, especially in the transportation terminals such as railway stations, bus terminals, airports and so forth, where large crowd gathers and transfers. To have a safe and comfortable movement in normal situation and also a quick evacuation in emergency situation, pedestrian movement patterns should be analysed and modelled properly.PurposeOnce the behaviour of pedestrians is established in terms of speed and density with respect to the environment, even for the colossal systems, the pedestrian flow characteristics can be modelled by applying extremely efficient simulations. The main modelling element in the context of flow models is the fundamental relationship among speed, flow and density. The objective of this study is to review the fundamental diagrams of pedestrian flow characteristics developed for various flow types and geometric elements. This paper also discusses the design values of flow parameters and walking speeds of pedestrians at various facilities.MethodsIn order to achieve the goal of this paper, we presented a systematic review of fundamental diagrams of pedestrian flow characteristics developed by using various approaches such as field, experimental and simulation.ConclusionsAfter a thorough review of literature, this paper identifies certain research gaps which provides an opportunity to enhance the understanding of fundamental diagrams of pedestrian flow characteristics.

Double diffusive flow of a hydromagnetic nanofluid in a rotating channel with Hall effect and viscous dissipation: Active and passive control of nanoparticles

The investigation of simultaneous effects of Hall current and viscous dissipation on three-dimensional magnetohydrodynamic nanofluid flow in a horizontal rotating channel with active and passive control of nanoparticles, is carried out. The lower sheet is considered stretching while the upper sheet is kept fixed. Mathematical model is developed using boundary layer and scale analysis approach. Similarity transformation technique is employed to translate the governing partial differential equations into ordinary differential equations. The bvp4c solver of MATLAB is employed to solve transformed equations. Computations for nanofluid velocity, nanofluid temperature distribution and distribution of nanoparticles along with skin friction co-efficient and Nusselt number, are carried out for a range of values of pertinent flow parameters. A comparative analysis of effect of CuO and Al2O3 nanoparticles on velocity, temperature, nanoparticle distribution, skin friction coefficient and Nusselt number is carried out. Rate of heat transfer at the lower sheet is observed to be a decreasing function of magnetic field whereas this physical quantity is getting enhanced as the volume fraction of nanoparticles are increased.

Hydromagnetic thin film flow of Casson fluid in non-Darcy porous medium with Joule dissipation and Navier’s partial slip

In this paper, the effects of viscous and Ohmic heating and heat genera-tion/absorption on magnetohydrodynamic flow of an electrically conducting Casson thin film fluid over an unsteady horizontal stretching sheet in a non-Darcy porous medium are investigated. The fluid is assumed to slip along the boundary of the sheet. Similar-ity transformation is used to translate the governing partial differential equations into ordinary differential equations. A shooting technique in conjunction with the 4th order Runge-Kutta method is used to solve the transformed equations. Computations are car-ried out for velocity and temperature of the fluid thin film along with local skin friction coefficient and local Nusselt number for a range of values of pertinent flow parameters. It is observed that the Casson parameter has the ability to enhance free surface velocity and film thickness, whereas the Forchheimer parameter, which is responsible for the inertial drag has an adverse effect on the fluid velocity inside the film. The velocity slip along the boundary tends to decrease the fluid velocity. This investigation has various applications in engineering and in practical problems such as very large scale integration (VLSI) of electronic chips and film coating.

HYDROMAGNETIC OLDROYD FLUID FLOW PAST A FLAT SURFACE WITH DENSITY AND ELECTRICAL CONDUCTIVITY STRATIFICATION

An usteady stratified flow of viscoelastic fluid past an inifnite flat surafce has been studied in presence of applied magnetic field. The visco-elastic fluid flow is characterized by Oldroyd fluid model contaning the rheological parameters: retardation and relaxation parameters. A magnetic field of strength B0 is applied along the transverse direction to surface. Fluidic properties like density, viscosity and electrical conductivity are assumed to vary along the axis of gravity. The governing equations of motion are solved analytically using separation of variable method. Results are discussed graphically and in tabular form for various values of flow parameters involved in the problem.

HYDROMAGNETIC NATURAL CONVECTION FLOW IN A NON-DARCY MEDIUM WITH SORET AND DUFOUR EFFECTS PAST AN INCLINED STRETCHING SHEET

The investigation of magnetohydrodynamic natural convection flow of an incompressible, electrically conducting, viscous, chemically reactive, and heat-absorbing fluid with combined heat and mass transfer past an inclined linearly stretching sheet when heat and mass fluxes are variable in nature, considering thermodiffusion and diffusion-thermo effects for the Forchheimer extended Darcy model, is carried out. To ease the analysis and process of computation, similarity transformation is used to convert the governing partial differential equations into ordinary differential equations. The Green–Swigert technique in conjunction with the Runge–Kutta fourth-order method is used to solve the transformed equations. Detailed computations for fluid velocity, fluid temperature, and species concentration as well as wall velocity gradient, wall temperature gradient, and wall concentration gradient are carried out for a range of values of pertinent flow parameters to analyze the physics of the flow. Increasing Forchheimer number (local inertia parameter) leads to a fall in fluid velocity because of a corresponding rise in Forchheimer impedance. The kind of study we have performed here has various applications in engineering and may have a bearing on problems of practical interest, namely, inclined plate clarifiers, oil–water separators, sedimentation equipment such as inclined plate settlers, fabrication of thin film, and so on.

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.

Visualization and research of gas-liquid two phase flow structures in cylindrical channel

Two-phase flows are commonly found in many industries, especially in systems, where efficient and correct functioning depend on specific values of flow parameters. In thermal engineering and chemical technology the most popular types of two-phase mixture are gas-liquid or liquid-vapour mixtures. Bubbles can create in flow different structures and determine diverse properties of flow (velocity of phase, void fraction, fluctuations of pressure, pipe vibrations, etc.). That type of flow is difficult to observe, especially in liquid-vapour mixture, where vapour is being made by heating the medium. Production of vapour and nucleation process are very complicated issues, which are important part of two-phase flow phenomenon. Gas-liquid flow structures were observed and described with figures, but type of structure depends on many parameters. Authors of this paper made an attempt to simulate gas-liquid flow with air and water. In the paper there was presented specific test stand built to observe two-phase flow structures, methodology of experiment and conditions which were maintained during observation. The paper presents also the structures which were observed and the analysis of results with reference to theoretical models and diagrams available in literature.

INFLUENCE OF SLIP CONDITION ON RADIATIVE MHD FLOW OF A VISCOUS FLUID IN A PARALLEL POROUS PLATE CHANNEL IN PRESENCE OF HEAT ABSORPTION AND CHEMICAL REACTION

The present investigation deals, heat and mass transfer characteristics with the effect of slip on the hydromagnetic pulsatile flow through a parallel plate channel filled with saturated porous medium. Based on the pulsatile flow nature, exact solution of the governing equations for the fluid velocity, temperature and concentration are obtained by using two term perturbation technique subject to physically appropriate boundary conditions. The expressions of skin friction, Nusselt number and Sherwood number are also derived. The numerical values of the fluid velocity, temperature and concentration are displayed graphically whereas those of shear stress, rate of heat transfer and rate of mass transfer at the plate are presented in tabular form for various values of pertinent flow parameters. By increasing the slip parameter at the cold wall the velocity increases whereas the effect is totally reversed in the case of shear stress at the cold wall.

UNSTEADY HYDROMAGNETIC HEAT AND MASS TRANSFER NATURAL CONVECTION FLOW PAST AN EXPONENTIALLY ACCELERATED VERTICAL PLATE WITH HALL CURRENT AND ROTATION IN THE PRESENCE OF THERMAL AND MASS DIFFUSIONS

In the present analytical study, we have considered unsteady hydromagnetic heat and mass transfer natural convection flow of an electrically conducting, heat absorbing and chemically reacting fluid past an exponentially accelerated vertical plate in a uniform porous medium taking Hall current and rotation into account. The species concentration near the plate is considered to be varies linearly with time. Two particular cases for plate temperature are considered i.e. (i) plate temperature is uniform and (ii) plate temperature varies linearly with time and after some time it is maintained at uniform temperature. The coupled partial differential equations governing the fluid flow problem are solved analytically for fluid velocity, temperature and species concentration using Laplace transform method. To examine the physical characteristic of this problem the graphs for velocity, temperature, species concentration, skin friction, Nusselt number and Sherwood number distributions are computed and generated for various values of different pertinent flow parameters. It is observed that for small thermal diffusion, the free stream value of velocity and temperature are achieved nearer to the plate in comparison to that for large thermal diffusion.

Free convective heat transfer with hall effects, heat absorption and chemical reaction over an accelerated moving plate in a rotating system

The unsteady MHD free convective heat and mass transfer flow of an electrically conducting, viscous and incompressible fluid over an accelerated moving vertical plate in the presence of heat absorption and chemical reaction with ramped temperature and ramped surface concentration through a porous medium in a rotating system is studied, taking Hall effects into account. The governing equations are solved analytically with the help of Laplace transform technique. The unified closed-form expressions are obtained for fluid velocity, fluid temperature, species concentration, skin friction, Nusselt number and Sherwood numbers. The effects of various parameters on fluid velocity, fluid temperature and species concentration are discussed by graphs whereas numerical values of skin friction, Nusselt and Sherwood numbers are presented in tabular form for different values of pertinent flow parameters. The numerical results are also compared with free convective flow near ramped temperature plate with ramped surface concentration with the corresponding flow near isothermal plate with uniform surface concentration.

Hydromagnetic flow of heat absorbing and radiating fluid over exponentially stretching sheet with partial slip and viscous and Joule dissipation

Purpose An investigation of hydromagnetic two dimensional boundary layer flow with heat transfer of a viscous, incompressible, electrically conducting, heat absorbing and optically thick heat radiating fluid over a permeable exponentially stretching sheet considering the effects of viscous and Joule dissipations in the presence of velocity and thermal slip is carried out. Design/methodology/approach Using similarity transform, governing differential equations representing mathematical model of the problem are solved with the help of fourth-order Runge-Kutta method along with shooting technique. Numerical solutions of fluid velocity and fluid temperature are depicted graphically for various values of pertinent flow parameters whereas numerical values of wall velocity gradient and wall temperature gradient are displayed graphically for various values of pertinent flow parameters. Findings Numerical results obtained in this paper are compared with earlier published results and are found to be in excellent agreement. Magnetic field and suction tend to enhance the wall velocity gradient whereas dimensionless co-ordinate, injection and velocity slip factor have reverse effect on it. Suction and heat absorption tend to enhance wall temperature gradient whereas magnetic field, velocity slip factor, injection, thermal radiation, thermal slip factor and viscous dissipation have reverse effect on it. Originality/value The investigation of this problem may have bearing in several engineering processes such as extrusion of plastic sheet, annealing and tinning of copper wire, paper production, crystal growing and glass blowing, continuous casting of metals and spinning of fibers.

Study on Periodic MHD Flow with Temperature Dependent Viscosity and Thermal Conductivity past an Isothermal Oscillating Cylinder

Temperature dependent viscosity and thermal conducting heat and mass transfer flow with chemical reaction and periodic magnetic field past an isothermal oscillating cylinder have been considered. The partial dimensionless equations governing the flow have been solved numerically by applying explicit finite difference method with the help Compaq visual 6.6a. The obtained outcome of this inquisition has been discussed for different values of well-known flow parameters with different time steps and oscillation angle. The effect of chemical reaction and periodic MHD parameters on the velocity field, temperature field and concentration field, skin-friction, Nusselt number and Sherwood number have been studied and results are presented by graphically. The novelty of the present problem is to study the streamlines by taking into account periodic magnetic field.

Heat and Mass Transfer Effects on Unsteady MHD Natural Convection Flow of a Chemically Reactive and Radiating Fluid through a Porous Medium Past a Moving Vertical Plate with Arbitrary Ramped Temperature

Investigation of unsteady hydromagnetic natural convection flow with heat and mass transfer of a viscous, incompressible, electrically conducting, chemically reactive and optically thin radiating fluid past an exponentially accelerated moving vertical plate with arbitrary ramped temperature embedded in a fluid saturated porous medium is carried out. Exact solutions of momentum, energy and concentration equations are obtained in closed form by Laplace transform technique. The expressions for the shear stress, rate of heat transfer and rate of mass transfer at the plate for both ramped temperature and isothermal plates are derived. The numerical values of fluid velocity, fluid temperature and species concentration are displayed graphically whereas those of shear stress, rate of heat transfer and rate of mass transfer at the plate are presented in tabular form for various values of pertinent flow parameters. It is found that, for isothermal plate, the fluid temperature approaches steady state when t  1.5 . Consequently, the rate of heat transfer at isothermal plate approaches steady state when t  1.5 .

Non-Newtonian Effects on Hydromagnetic Dusty Stratified Fluid Flow Through a Porous Medium with Volume Fraction

An unsteady hydro-magnetic Couette flow of dusty non-Newtonian stratified fluid through a porous medium bounded by two parallel plates has been investigated in presence of volume fraction. Lower plate is kept fixed and the upper plate is moving with some velocity. The non-Newtonian fluid flow is characterized by Walters liquid (Model $$ B^{\prime } $$ ). Effects of exponentially varying density, viscosity, visco-elasticity, electrical conductivity and dust particle density have been considered in the problem. A magnetic field of strength B 0 is applied along the transverse direction to the plate. Governing equations of motion are solved analytically for various values of flow parameters involved in the solution. Effects of visco-elasticity on velocity profile, skin friction have been studied graphically. Also, effects of stratification parameter and volume fraction in both Newtonian and non-Newtonian fluid flows have been analysed.

Unsteady MHD free convection flow with Hall effect of a radiating and heat absorbing fluid past a moving vertical plate with variable ramped temperature

Abstract Unsteady hydromagnetic free convection flow of a viscous, incompressible, electrically conducting, optically thick radiating and heat absorbing fluid past an accelerated moving vertical plate with variable ramped temperature is investigated. Exact solution of the governing equations for the fluid velocity and fluid temperature are obtained by Laplace transform technique. The numerical values of primary and secondary fluid velocities and fluid temperature are displayed graphically whereas those of shear stress and rate of heat transfer at the plate are presented in tabular form for various values of pertinent flow parameters.

Mixed convection hydromagnetic flow in a rotating channel with Hall and wall conductance effects

Mixed convection hydromagnetic flow of a viscous, incompressible, electrically and thermally conducting fluid in a rotating channel taking Hall current into account is studied. Fluid flow within the channel is induced due to an applied pressure gradient acting along the longitudinal axis of the plates of the channel. Exact solution of the governing equations is obtained in closed form. Expressions for the shear stress and critical Grashof number at the plates of the channel due to primary and secondary flows and mass flow rates in the primary and secondary flow directions are also derived. Asymptotic behavior of the solution for fluid velocity and induced magnetic field is analyzed for large values of rotation parameter K2 and magnetic parameter M2 to gain some physical insight into flow pattern. Heat transfer characteristics of fluid flow are considered taking viscous and Joule dissipations into account. Numerical solution of energy equation and numerical values of rate of heat transfer at the plates of the channel are computed with the help of MATLAB software. The numerical values of fluid velocity, induced magnetic field and fluid temperature are displayed graphically versus channel width variable η for various values of pertinent flow parameters whereas that of shear stress and critical Grashof number at the plates of the channel due to primary and secondary flows, mass flow rates in the primary and secondary flow directions and rate of heat transfer at the plates of the channel are presented in tabular form for various values of pertinent flow parameters.

Unsteady Hydromagnetic Natural Convection Flow of a Heat Absorbing Fluid within a Rotating Vertical Channel in Porous Medium with Hall Effects

Unsteady hydromagnetic natural convection flow of a viscous, incompressible, electrically conducting and temperature dependent heat absorbing fluid confined within a parallel plate rotating vertical channel in porous medium is investigated. Fluid flow within the channel is induced due to impulsive movement of one of the plates of the channel. Exact solution for the governing equations for fluid velocity and fluid temperature are obtained by Laplace transform technique. The expressions for the shear stress at the moving plate due to primary and secondary flows and those of rate of heat transfer at the moving and stationary plates are also derived. In order to gain some physical insight into the flow pattern, asymptotic behavior of the solution for fluid velocity and fluid temperature are analyzed for small and large values of time. The numerical values of primary and secondary fluid velocities and fluid temperature are displayed graphically whereas those of shear stress at the moving plate and rate of heat transfer at both the moving and stationary plates are presented in tabular form for various values of pertinent flow parameters.