scholarly journals Thermal properties and time-dependent flow behavior of a viscous fluid

2019 ◽  
Vol 51 (2) ◽  
pp. 180-184
Author(s):  
M. Imran Khan ◽  
T. Hayat ◽  
M. Ijaz Khan ◽  
T. Yasmeen
Keyword(s):  
Heat Transfer ◽  
Flow Behavior ◽  
Heat Transfer Process ◽  
Stretching Surface ◽  
Surface Drag ◽  
Electric And Magnetic Fields ◽  
Unsteady Stretching Surface ◽  
Opposite Situation ◽  
Dependent Flow ◽  
Thermal Radiation Effect

Our goal in this attempt is to model a nonlinear stretchable flow of a radiative viscous liquid with magnetohydrodynamics. Flow caused is due to a unsteady stretching surface with variable thickness. Consideration of thermal radiation effect characterizes the heat transfer process. Induced electric and magnetic fields are not accounted for. Appropriate transformations gave nonlinear systems. Modern methodology, i.e., НAM, is implemented for the computational process. Velocity and temperature are plotted for influential variables which are important in this problem. Moreover, surface drag force and heat transfer rate are computed and discussed. Velocity field is noted to decay the function of the larger Hartman number whereas opposite situation for temperature is examined via larger radiation parameter.

Heat transfer over an unsteady stretching surface with prescribed heat flux

2008 ◽  
Vol 86 (6) ◽  
pp. 853-855 ◽  
Author(s):  
A Ishak ◽  
R Nazar ◽  
I Pop
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Differential Equations ◽  
Nonlinear Partial Differential Equations ◽  
Method Comparison ◽  
Temperature Fields ◽  
Stretching Surface ◽  
Keller Box Method ◽  
Unsteady Stretching Surface ◽  
Layer Flow

The unsteady laminar boundary-layer flow over a continuously stretching surface in a viscous and incompressible quiescent fluid is studied. The unsteadiness in the flow and temperature fields is caused by the time dependence of the stretching velocity and the surface heat flux. The nonlinear partial differential equations of continuity, momentum, and energy, with three independent variables, are reduced to nonlinear ordinary differential equations, before they are solved numerically by the Keller-box method. Comparison with available data from the open literature as well as the exact solution for the steady-state case of the present problem is made, and found to be in good agreement. Effects of the unsteadiness parameter and Prandtl number on the flow and heat transfer characteristics are thoroughly examined.PACS No.: 47.15.Cb

Numerical Investigations of Forced Convection From Rectangular Coiled Pipes

2007 ◽  
Author(s):  
Ibrahima Conte´ ◽  
Xiao-Feng Peng ◽  
Zhen Yang
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Secondary Flow ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Heat Transfer Process ◽  
Single Vortex ◽  
Staggered Arrangement ◽  
Inclination Angles ◽  
Turbulent Air Flow

Investigations are done to numerically study forced convective heat transfer from the flow inside a rectangular coiled pipe, as micro-scale heat exchange device with staggered arrangement, to the external flow around the pipe. The commercial CFD software Fluent 6.0 is used as the solver. The problems considered were three-dimensional laminar flow of the refrigerant R141B through the tube and turbulent air flow exterior to the tube. The studied coiled pipe was composed of four rows among which two rows were encompassed in a large rectangular coil and the other two were in an inner smaller rectangular coil. The results showed remarkable differences in the flow behavior and heat transfer for different rows of tubes. The secondary flow in the tubes bends of the larger rectangular coil is very weak compared to that of the inner rectangular coil. Better heat transfer process occurred through the tubes of the second row where the higher values of the fluid temperatures were observed in the pipe. The results showed the effects of the straight tubes inclination angle on the flow behavior in rectangular coiled pipes. The shape of the secondary flow is changed from a couple of vortices in the case of smaller angle (α = 9°) to a single vortex in the case of larger angle (α = 45°). The results also showed the rotation of the maximum axial velocity due to the increase in the straight tubes inclination angles. The results are in good agreement with previous numerical and experimental works on laminar flow in helical coil pipe.

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