Begell House Inc.
Computational Thermal Sciences: An International Journal
CTS
1940-2503
8
4
2016
NUMERICAL SIMULATION OF BLOOD FLOW IN HEALTHY ARTERIES BY USE OF THE SISKO MODEL
309-320
Shahin
Shareghi
Department of Mechanical Engineering, Khomeinishahr Branch, Islamic Azad University, Khomeinishahr, Iran
Davood
Toghraie
Department of Mechanical Engineering, Khomeinishahr Branch, Islamic Azad University, Khomeinishahr, Iran
Blood flow simulations in computational fluid dynamics (CFD) are seen as a very attractive solution for diagnosing diseases. The main objective of this work is to simulate blood flow in healthy arteries. The governing equations for the Sisko model are presented in cylindrical coordinates. The finite volume method is used for the velocity and wall shear stress at healthy arteries. It is observed that the velocity profile increases due to an increase in Sisko fluid parameters and the radius of healthy arteries. With regard to the fact that blood flow in healthy arteries is non-Newtonian, the fluid obeys the Sisko fluid model. We contemplate that due to an increase in Sisko fluid parameters and the radius of healthy arteries, the wall shear stress profile increases and decreases, respectively.
TRANSCRITICAL CARBON DIOXIDE FLOW IN A TUBULAR HEAT EXCHANGER: APPLICATIONS IN WASTE HEAT RECOVERY
321-336
Bakhtier
Farouk
Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, Pennsylvania 19104, USA
Nusair
Hasan
Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, Pennsylvania 19104, USA
Nonlinear thermophysical property variations in near-critical fluids give rise to large heat transfer coefficients, thus making them an ideal fluid for harnessing waste heat. Heat recovery from a power plant steam condenser by utilizing a transcritical flow of carbon dioxide in a bottoming cycle is considered. Thermal transport characteristic of transcritical carbon dioxide flowing in a tubular heat exchanger is numerically investigated. Transcritical carbon dioxide flowing in a circular cross-section tube with the outer wall heated by condensing steam (an isothermal wall) is considered for both horizontal and vertical configurations. The thermal transport characteristics for both configurations are examined. Due to the rapid and large variations of thermophysical properties with small temperature changes, transcritical fluid flows are usually characterized by the development of mixed convection and buoyancy plays a significant role in the flow dynamics. The effect of buoyancy on the thermal transport characteristics is also investigated. The predicted results from the present study can be used in designing waste-heat-driven organic Rankin cycles for power generation.
ON MIXED CONVECTION IN AN INCLINED LID-DRIVEN CAVITY WITH SINUSOIDAL HEATED WALLS USING THE ISPH METHOD
337-354
Abdelraheem M.
Aly
Department of Mathematics, Faculty of Science, Abha, King Khalid University, Saudi Arabia;
Department of Mathematics, Faculty of Science, South Valley University, Qena, Egypt
Ali J.
Chamkha
Department of Mechanical Engineering, Prince Sultan Endowment for Energy and
Environment, Prince Mohammad Bin Fahd University, Al-Khobar 31952, Kingdom of Saudi
Arabia; RAK Research and Innovation Center, American University of Ras Al Khaimah, United Arab Emirates, 10021
Sang-Wook
Lee
School of Mechanical Engineering, University of Ulsan, Ulsan, South Korea
Ali F.
Al-Mudhaf
Manufacturing Engineering Department, The Public Authority for Applied Education and Training, P. O. Box 42325, Shuweikh, 70654 Kuwait
Simulation of mixed convection in an inclined lid-driven square cavity has been investigated using an incompressible
smoothed particle hydrodynamics (ISPH) method. In this study, the boundary conditions on the inclined lid-driven
square cavity have been introduced for two different cases of sinusoidal heated and isothermal walls. The governing
equations are discretized and solved using the ISPH method. In the ISPH method, the evaluated pressure is stabilized
by relaxed density invariance in solving the pressure Poisson equation. The solutions represented in isothermal lines and flow profiles have been studied with different values of Richardson number, phase deviation of sinusoidal heating, and cavity inclination angle. It is found that the shear force induced by lid-movement plays a more dominant role than cavity inclination angle. A set of graphical results is presented and discussed to illustrate the effects of the presence of current parameters on the flow and heat transfer characteristics. The efficiency of the current ISPH method is tested by comparison with reference results.
INFLUENCE OF SURFACE MASS TRANSFER ON THE STABILITY OF FORCED CONVECTION FLOW OVER A HORIZONTAL FLAT PLATE
355-369
Abdelghani
LAOUER
Faculty of Exact Sciences and Informatics, University of Mohamed Seddik Ben Yahia
El Hacene
Mezaache
Laboratoire de Physico-Chimie des Surfaces et Interfaces, Université de Skikda, BP. 26, Skikda
21000, Algérie
Salah
Laouar
Laboratoire de Physico-Chimie des Surfaces et Interfaces, Université de Skikda, BP. 26, Skikda 21000, Algérie
The effects of suction or blowing surface mass transfer on the stability of two-dimensional laminar forced convection
flow over a horizontal flat plate are studied numerically by using temporal linear stability analysis. The mean flow
is assumed similar, two-dimensional laminar boundary layer. The mean velocity profiles are obtained numerically
for the case of suction and blowing. The flow disturbance modes are governed by the Orr-Sommerfeld equation. This
equation is solved numerically by using the Chebyshev spectral collocation method, which is based on the eigenfunction expansion in terms of Chebyshev polynomials, collocation points, and the subsequent solution of the resulting generalized eigenvalue problem with the QZ algorithm. The obtained numerical results are validated by comparison with some previous works. The stability curves, critical Reynolds numbers, eigenvalue spectrum, and eigenfunctions are presented for a range of wall stream function values.
SHIELDING OF FIRE RADIATION WITH THE USE OF MULTI-LAYERED WATER MIST CURTAINS: PRELIMINARY ESTIMATES
371-380
Leonid A.
Dombrovsky
Joint Institute for High Temperatures, 17A Krasnokazarmennaya Str., Moscow,
111116, Russia; Tyumen State University, 6 Volodarsky Str., Tyumen, 625003, Russia
Siaka
Dembele
Fire, Explosion and Fluid Dynamics Research Group, School of Mechanical and Automotive Engineering, Kingston University, London SW15 3DW, UK
Jennifer X.
Wen
Faculty of Engineering, Kingston University, Friars Avenue, Roehampton Vale, London, SW15 3DW, United Kingdom; School of Engineering, University of Warwick, Coventry CV4 7AL, UK
An approximate solution for the complete problem of attenuation of fire radiation by water mist is presented. This solution is based on simplified approaches for the spectral radiative properties of water droplets, the radiative transfer in the absorbing and scattering mist, and transient heat transfer taking into account partial evaporation of water mist. An analysis of the example problem makes it possible to recommend a decrease in the size of supplied water droplets with the distance from the irradiated surface of the mist layer. This can be achieved with the use of a multi-layered mist curtain.
The advantage of this engineering solution is also confirmed by numerical calculations.
NUMERICAL STUDY OF DOUBLE-DIFFUSIVE CONVECTION IN A HEATED LID-DRIVEN CAVITY WITH MASS DIFFUSIVE SIDE WALLS
381-398
Nithish
Reddy
Mechanical & Industrial Engineering Department, Indian Institute of Technology Roorkee, Roorkee − 247 667, India
K.
Murugesan
Mechanical & Industrial Engineering Department, Indian Institute of Technology Roorkee, Roorkee
− 247 667, India
In this paper double-diffusive mixed convection in a heated lid driven cavity has been studied numerically using a
finite element base code. Double-diffusive convection phenomenon is observed in many process industrial applications where essentially hot air is used to remove moisture or to aid any other process. In the current problem numerical investigations have been conducted on double-diffusive convection in a hot lid driven cavity with mass diffusive side walls. Galerkin's weighted residual method has been implemented to reduce the governing equations, namely vorticity transport, velocity, Poisson, energy, and solutal equations into weak form. Results have been obtained for different parameters like Reynolds number ranging from 100 to 500, Richardson number ranging from 0.1 to 3.0, and buoyancy ratio −50 to +50. Results show that an increase in Richardson number increased heat transfer rates when operated in a positive buoyancy ratio regime and the transverse is observed when operated in a negative regime. Increase in strength of buoyancy forces s to formation of a number of secondary circulations in the cavity, while an increase in inertial forces improved convective heat transfer rate from lid more effectively when buoyancy forces were weaker.