Study of Laminar Forced Convection of Radiating Gas Over an Inclined Backward Facing Step Under Bleeding Condition Using the Blocked-Off Method

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
A. B. Ansari ◽  
S. A. Gandjalikhan Nassab
Keyword(s):  
Forced Convection ◽  
Gas Flow ◽  
Radiation Heat Transfer ◽  
Simple Algorithm ◽  
Temperature Fields ◽  
Convection Flow ◽  
Backward Facing Step ◽  
Cartesian Coordinate ◽  
Volume Method ◽  
Laminar Forced Convection

This paper presents a numerical investigation for laminar forced convection flow of a radiating gas over an inclined backward facing step in a horizontal duct subjected to bleeding condition. The fluid is treated as a gray, absorbing, emitting, and scattering medium. The two-dimensional Cartesian coordinate system is used to simulate flow over inclined surface by considering the blocked-off region in regular grid. The governing differential equations consisting the momentum and energy are solved numerically by the computational fluid dynamics techniques to obtain the velocity and temperature fields. Discretized forms of these equations are obtained by the finite volume method and solved using the SIMPLE algorithm. Since the gas is considered as a radiating medium, convection, conduction, and radiation heat transfer mechanisms take place simultaneously in the gas flow. For computation of the radiative term in the gas energy equation, the radiative transfer equation is solved numerically by the discrete ordinate method to find the radiative heat flux distribution inside the radiating medium. The effects of bleeding coefficient, inclination angle, optical thickness, albedo coefficient, and the radiation-conduction parameter on the flow and temperature distributions are carried out.

Combined Mixed Convection and Radiation Heat Transfer in an Obstacle Wall Mounted Lid-driven Cavity

2016 ◽  
Vol 17 (6) ◽  
pp. 277-289 ◽  
Author(s):  
M. Moein Addini ◽  
S. A. Gandjalikhan Nassab
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Gas Flow ◽  
Radiation Heat Transfer ◽  
Simple Algorithm ◽  
Bottom Wall ◽  
Temperature Fields ◽  
Convection Flow ◽  
Driven Cavity ◽  
Laminar Mixed Convection

AbstractThis paper presents a numerical investigation for laminar mixed convection flow of a radiating gas in a lid-driven cavity with a rectangular-shaped obstacle attached on the bottom wall. The vertical walls of the square cavity are assumed to be adiabatic, while other walls of cavity and obstacle are kept at constant temperature. The fluid is treated as a gray, absorbing, emitting and scattering medium. The governing differential equations consisting the continuity, momentum and energy are solved numerically by the computational fluid dynamics techniques to obtain the velocity and temperature fields. Discretized forms of these equations are obtained by the finite volume method and solved using the SIMPLE algorithm. Since the gas is considered as a radiating medium, besides convection and conduction, radiative heat transfer also takes place in the gas flow. For computation of the radiative term in the gas energy equation, the radiative transfer equation is solved numerically by the discrete ordinate method. The streamline and isotherm plots and the distributions of convective, radiative and total Nusselt numbers along the bottom wall of cavity are presented. The effects of Richardson number, obstacle location, radiation–conduction parameter, optical thickness and albedo coefficient on the flow and temperature distributions are carried out. Comparison between the present numerical results with those obtained by other investigators in the cases of conduction–radiation and pure convection systems shows good consistencies.

scholarly journals Forced convection of radiating gas over an inclined backward facing step using the blocked-off method

2013 ◽  
Vol 17 (3) ◽  
pp. 773-786 ◽  
Author(s):  
Amir Ansaria ◽  
Nassaba Gandjalikhan
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Gas Flow ◽  
Control Volume ◽  
Research Work ◽  
Temperature Fields ◽  
Discrete Ordinates ◽  
Convection Flow ◽  
Governing Equations ◽  
Backward Facing Step

The present work investigates the laminar forced convection flow of a radiating gas over an inclined backward facing step (BFS) in a horizontal duct. The momentum and energy equations are solved numerically by the CFD techniques to obtain the velocity and temperature fields. Since, the twodimensional Cartesian coordinate system is used to solve the governing equations; the flow over inclined surface is simulated by considering the blocked-off region in regular grid. Discretized forms of the governing equations in the (x,y) plane are obtained by the control volume method and solved using the SIMPLE algorithm. The fluid is treated as a gray, absorbing, emitting and scattering medium. Therefore, all of the convection, conduction and radiation heat transfer mechanisms take place simultaneously in the gas flow. For computation of the radiative term in the gas energy equation, the radiative transfer equation (RTE) is solved numerically by the discrete ordinates method (DOM) to find the radiative heat flux distribution inside the radiating medium. In the numerical results, effects of inclination angle, optical thickness, scattering albedo and the radiation-conduction parameter on the heat transfer behavior of the convection flow are investigated. This research work is a new one in which a combined convection-radiation thermal system with a complex flow geometry is simulate by efficient numerical techniques.

Numerical Investigation of Forced Laminar Convection Flow of Nanofluids Over a Backward Facing Step Under Bleeding Condition

2012 ◽  
Vol 28 (2) ◽  
pp. N7-N12 ◽  
Author(s):  
M. S. Pour ◽  
S. A. G. Nassab
Keyword(s):  
Fluid Dynamic ◽  
Simple Algorithm ◽  
Nano Particles ◽  
Temperature Fields ◽  
Convection Flow ◽  
Convective System ◽  
Test Case ◽  
Backward Facing Step ◽  
Laminar Convection ◽  
Energy Equations

AbstractIn this paper, single-phase laminar forced convection of nanofluids flow over a 2D horizontal backward facing step (BFS) subjected to bleeding condition (suction/blowing) is investigated numerically. The continuity, momentum and energy equations are solved by computational fluid dynamic (CFD) technique, while the SIMPLE algorithm is employed for pressure-velocity coupling. Various volume fractions of nano-particles are dispersed in a base fluid (water) to produce different types of nanoflouids. In each test case, the velocity and temperature fields are computed to verify the hydrodynamic and thermal behaviors of convective system. Besides, the distributions of Nusselt number and friction coefficient at the stepped wall are obtained. Comparison between the present numerical results with experiment shows a good consistency.

Simulation of three-dimensional laminar forced convection flow of a radiating gas over an inclined backward-facing step in a duct under bleeding condition

2012 ◽  
Vol 227 (2) ◽  
pp. 332-345 ◽  
Author(s):  
M Atashafrooz ◽  
SA Gandjalikhan Nassab
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Discrete Ordinates ◽  
Convection Flow ◽  
Backward Facing Step ◽  
Forced Convection Flow ◽  
Laminar Forced Convection

This study presents a numerical analysis of three-dimensional laminar forced convection flow of a radiating gas over an inclined backward-facing step in a rectangular duct under bleeding condition. The fluid is treated as a gray, absorbing, emitting, and scattering medium. The three-dimensional Cartesian coordinate system is used to solve the governing equations which are the conservations of mass, momentum, and energy. These equations are solved numerically using the computational fluid dynamic techniques to obtain the temperature and velocity fields, while the blocked-off method is employed to simulate the incline surface. Discretized forms of these equations are obtained by the finite volume method and solved using the SIMPLE algorithm. Since the gas is considered as a radiating medium, besides the convective and conductive terms in the energy equation, the radiative term also presented. For computation of this term, the radiative transfer equation is solved numerically by the discrete ordinates method to find the divergence of radiative heat flux distribution inside the radiating medium. By this numerical procedure, the role of radiation heat transfer on convection flow of a radiating gas which has many engineering applications (for example in heat exchangers and combustion chambers) is studied in detail. Beside, the effects of bleeding coefficient, albedo coefficient, optical thickness, and the radiation–conduction parameter on heat transfer behavior of the system are investigated. Comparison of numerical results with the available data published in the open literature shows a good agreement.

Forced Convection inside a Vertical Circular Cylinder with an Inner Coaxial Rectangular Cylinder

2021 ◽  
Vol 406 ◽  
pp. 25-35
Author(s):  
Hamad Ahmed Boughezala ◽  
Said Bouabdallah ◽  
Ali Boukhari
Keyword(s):  
Reynolds Number ◽  
Velocity Field ◽  
Circular Cylinder ◽  
Forced Convection ◽  
Simple Algorithm ◽  
Ansys Fluent ◽  
Rectangular Cylinder ◽  
Annular Gap ◽  
Volume Method ◽  
Laminar Forced Convection

In this work, we performed a numerical simulation of laminar forced convection and, in an annular space inside a vertical circular cylinder with an inner coaxial rectangular cylinder having an aspect ratio (height/radius) γ=2, filled with a liquid metal (Pr = 0.0023). Six annular gaps R =0.9, 0.8, 0.7, 0.6, 0.5 and 0.4 were studied. The governing equations are solved using the ANSYS Fluent code which is based on the finite volume method. SIMPLE algorithm is employed for the pressure-velocity coupled momentum equations. Two cases of the rotating parts of the cylinders are investigated and the effect of Reynolds number on the flow are examined. The obtained results of the forced convection show that the increase of the Reynolds number Re affects straightly on the structure of the flow wherever the velocity field are destabilized and the strongest stabilization of the velocity field occurs when the flow generated by the rotating of the circular cylinder and the rectangular cylinder.Keywords: forced convection, annular gap, circular cylinder, rectangular cylinder, co-rotating.

scholarly journals Analysis Of Field Synergy In Bottom Heated Lid Driven Cubical Cavity

2019 ◽  
Vol 128 ◽  
pp. 07007
Author(s):  
H.P. Rani ◽  
V. Narayana ◽  
Y. Rameshwar
Keyword(s):  
Forced Convection ◽  
Computational Cost ◽  
Convection Flow ◽  
Field Synergy ◽  
Governing Equations ◽  
Field Synergy Principle ◽  
Stream Functions ◽  
Forced Convective Flow ◽  
Volume Method ◽  
Cubical Cavity

This study presents an innovative visualization tool for the analysis of the mixed convection in a lid-driven air filled cubical cavity heated from below. The total energy of the flow in the cavity isvisualized based on the energy stream functions or energy streamlines. Also the heat transfer enhancement in the cavity is presented with an analogy between conduction and convection, namely, the field synergy principle. Flow is assumed to be driven by the vertical temperature gradient and by the top lid of the cavity, which is assumed to slide on its own plane at a uniform speed. The top and bottom walls are assumed to be isothermal and all other walls are thermally insulated. Non dimensional governing equations of this problem are solved by using the finite volume method. Established open source CFD package OpenFOAM is utilized to investigate the flow with respect to the control parameters arising in the system. The nonlinear terms arising in the governing equations are discretized with the NVD schemes. The convection differencing schemes namely, UPWIND, QUICK, SUPERBEE and SFCD discussed and are used to simulate the flow using MPI code. It is observed that the computational cost for all the differencing schemes get reduced tremendously when the MPI code is implemented. Also SFCD scheme gave the Nuseelt number values close to those available in the literature. Extensive numerical flow visualization is conducted for the Reynolds number (Re = 100, 400, 1000) and the Richardson number (Ri = 0.001, 1, 10), which categorize the free and forced convective flow, respectively. It is observed that for a fixed value of Re, as Ri increases, the average Nusselt number (Nu¯), decreases. This shows that the natural convection starts to prevail with an increasing of Ri. But, for a fixed Ri, as Re increases (Nu¯) increases and the forced convection mode becomes dominant, leading to a chaotic flow. Plots demonstrating the influences of Re and Ri in termsof the contours of the fluid streamlines, isotherms, vortex corelines, and field synergy principle. The synergy angle of buoyant-aiding flow is high while the buoyant-opposing flow is significantly less than that of forced convection flow.

Sign in / Sign up

Export Citation Format

Share Document