Week 5.1 - Non-Conformal Meshing
Problem statement: Cold plate is used to remove heat from 2 parallel hot plates emitting 200W of energy. Project statement: To set up Transient simulation to validate characteristics of Temperature, flow in internal flow in cold plate and external flow characteristics due to natural convection surrounding cold plate and heat sources.
Major Techniques used: 1. N/C meshing
2. Individual Object params
3. Setting up multiple fluid blocks(water, Air)
Geometry:
1. The geometry consists of Cold plate solid plate, fluid block represents fluid inside the cold plate with appropriate priority, else mesh will not be generated for fluid block.
2. Two pipes connecting inlet and outlet cold plate, fluid line inside the pipes has to be modelled as separate cylinderical fluid blocks to represent the fluid entering and leaving cold plate.
3. Two opening is created to simulate the fluid entering at 0.2m/s in inlet and another opening static pressure is set to 0Pa indicating external atmosphere.
4. 2 hot plates are modelled to generate 200W of heat energy on the sides of cold plates.
5. Default fluid is air and working fluid is set to water.
Mesh:
1. Initial mesh has been created with default setting to validate any possible problems with geometry and priority and found error indicating mesh is not generated in fluid inlet and outlet, which is rectified by changing mesh priority higher to those blocks.
2. Initial mesh created is of good quality but with higher mesh count due to mesh bleeding so N/C mesh is generated for cold plate which includes solid and fluid block regions.
3. Slack value of 3mm is given in all sides to capture near wall effects.
4. After Visual check of mesh, object params is defined for some regions for refinement.
5. HD mesh is generated with skewness 0.29 and face alignment 0.48, which is of higher quality than minimum requirement. hence meshing objective is reached.
SOLID & FLUID MESH DISPLAY
Solver setup:
1. The case is solved for 2 conditions, steady state to rule out any possibility of divergence and to make sure the solutions proceed smoothly and problem is solved for transient case.
2. Problem is solved for flow, temperature with inlet velocity of 0.2m/s.
3. Heat generation in hot plates set to 200W. Flow regime is turbulent so zero equation model is used with gravity to capture natural convection effects.
4. Advance solver setup includes body force due to natural convection problem, and double precision solver is used.
5. The steady state conditions in solved for 1000 iterations in which convergence is reached in 630 iterations.
6. Once the convergence is reached another solution is initiated for transient condition with time step of 0.1s for total of 70s. solution is carried out till convergence is reached for defined time steps with 2000+ iterations.
POST-PROCESSING:
FLUID BLOCK TEMPERATURE
SOLID BLOCK TEMPERATURE
VELOCITY VECTORS
CUT PLANE-TEMPERATURE CONTOURS
TEMPERATURE CONTOURS (TRANSIENT @ 71S)
Maximum temperatures:(STEADY STATE)
influ : 28.5149 C
inlet pipe : 28.9897 C
outflu : 29.3734 C
outlet pipe : 29.8597 C
cold plate solid block : 32.8041 C
fluid block : 32.6513 C
plate.1 : 32.8928 C
plate.1.1 : 32.8929 C
Maximum temperatures:(TRANSIENT @ 71 S)
influ : 23.1442 C
inlet pipe : 23.3426 C
outflu : 23.2633 C
outlet pipe : 23.4622 C
cold plate solid block : 24.8873 C
fluid block : 24.7945 C
plate.1 : 24.9565 C
plate.1.1 : 24.9565 C
Conclusion:
The steady and transient cases have been studied and found higher temperatures in cold plate surface as 32 deg but inlet and outlet temperature is relatively less, the same condition have been achieved with transient analysis.
Inference:
The inlet velocity is lower so increasing the inlet velocity will further increase the heat transfer rate which will cool down the sources efficiently.