Week 8 - Natural Convection-II

CHALLENGE:

Build the model as per the following information.

Mesh the model with nonconformal meshing

Solve the problem for natural convection.

MODEL:

1. The model have been created based on given drawing. and simplified to ICEPAK objects using spaceclaim.

2. Two grilles have been created in the bottom with direction allowing fluid flow inward.

3. One grille is placed in top with bigger size to allow hot air pass out.

4. This principle is based on the natural draft fluid flow due to density variation.

MESHING:

1. The initial mesh have been generated with default settings. and examined for further refinements.

2. Mesh bleeding was observed in domain so N/C assemblies have been created for the breakers.

3. The mesh type was changed to cartesian inorder to create high quality elements as all geometries are linear.

4. The above image shows the mesh from XYZ direction. mesh was finer to capture all physics.

5. The below images shows the quality of the mesh elements with Face alignment 0.93 and skewness is 0.77.

CASE SETUP:

1. The problem have been solved for natural convection case.

2. Joules heating is set up for bus bar with respective given current values.

3. Power dissipation is defined for all breakers.

4. Problem is solved with model based initialization to get better convergence.

4. The solution residuals shows better convergence characteristics. and the solution converged quickly.

POST PROCESSING:

1. The below image shows the cut plane in middle of domain with higher temperature in the top region.

2. The below image shows the temperature contours for all body in the domain.

3. The below image shows the particle traces based on velocity magnitude. with higher velocity value as 64m/s. The grilles position is important for natural convection to occur. and in this case it is efficient as temperature of components near inflow grilles are very less.

4. The below image shows the variation plot of temperature from one side of domain to another side. with highest temperature is reported in middle of the doamin. and it very less near the inflow grilles.

IMPRESSION:

1. The temperature is very high in incoming bus bars so it is recommended to solve the problem with radiation heat transfer to see changes.

2. It is also recommended to set up another set of grilles in the middle of the cabinet to further improve the heat transfer.