TITLE : HOTBOX EXAMPLE : Flow Through a Channel with a Single Heating Block on PCB
BY : CHAM Development Team - F Liu DATE : 1999 FOR : Demonstration Case PHOENICS Version : HOTBOX VR
NOTES : Three-dimensional, steady flow, mixed convection, conjugate heat transfer, Cartesian computational grid Description of the problem:
- Incoming air with uniform velocity and temperature flows over a heating component mounted on a thermally conducting board. The dimensions of the channel are 100mm(L) x 10mm(H) x 30mm(W); the component is of 6mm x 6mm x 2mm and mounted on the conducting board, whose thickness is 1mm and located on the floor. click here to see Overall view of the channel
- The incoming velocity and temperature are 0.1 m/s and 25°C, respectively, and the heating component has 0.5 W heat output, which gives a mixed convection flow regime; and all walls are assumed adiabatic.
- Thermal conductivities for the component, board and air are 30, 1 and 0.026 W/(m K), respectively.
Solution procedure:
- Turbulence is modelled by the LVEL method;
- Ideal gas law is employed and the buoyancy effect is included using Density-Difference method;
- Material properties are imported from the User-defined property file 'Props'; and
- Fixed pressure boundary condition is applied at the channel exit.
Results:
All the pictures as shown below are created via the Virtual Reality Graphic Interface, a strong feature of HOTBOX-VR.
1. Velocity vectors
Velocity vector across the component along the flow direction
Velocity vector within the cross-sections at several locations along the flow direction
Velocity vector across the component within the cross-section
Velocity vector within the cross-section at 30mm behind the componentFrom the figures above, the predicted velocity is symmetric along the x mid-plane, which is also evident from the temperature contours followed. The incoming air passes over the heating component and being heated, thus the flow presents slightly upward and this trend is persisted up to at the exit of the channel. This reveals a mixed convection flow regime between natural and forced.
2. Temperature contours
Temperature contour across the component along the flow direction
Temperature contour within the cross-sections at several locations along the flow direction
Temperature contour across the component within the cross-section
It is clearly seen that the circling air is cooling the component and the temperature distribution around it is very much following the flow pattern.
Conclusions:
- This case demonstrates how HOTBOX-VR handles mixed convection flow and heat transfer in a channel with a heating block;
- It also demonstrates how HOTBOX-VR treats the fluid with a variable density; and
