Week 5.1 - Non-Conformal Meshing and Solving a Cold plate model

Non-Conformal Meshing And Solving A Cold Plate Model

Aim: To perform the analysis for a two-heated plates model, cooled by water circulating inside the cold-plate cavity, as well as by air driven by natural convection externally. And separately meshed assemblies will be employed to reduce the overall mesh count in the domain.

Objective:

1. Generate the Mesh:
   1. Create non-conformal mesh assembly
   2. Use mesh separately option with slack values
   3. Use object parameters
   4. Generate mesh.

2. Numerical setting:
   1. Use problem set up wizard
   2. set no of iterations and convergence criteria
   3. Solve for Flow and Temperature and Radiation is off. The turbulence model is the Zero equation model.
   4. Set up the gravity vector
   5. Setup transient simulation with an initial velocity of 0.005 m /s in antigravity direction
   6. Set up monitor points in the model
   7. Save the model.
   8. Solve the model.

2. Examine and post-process the results:
   1. Plane cut
   2. Vector plot
   3. Temperature contour
   4. Object face

Theory:

The classic example of a heat exchanger is found in an internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and air flows past the coils, which cools the coolant and heats the incoming air. Another example is the heat sink, which is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant.

Geometry :

Cabinet:

First, we need to create the cabinet with the dimension 400 mm X 300 mm X 200 mm and the cabinet as an enclosure for the total geometry

Cold plate solid block:

The cold plate solid block was created accordingly as per the given dimensions in the challenge with a start point (50 mm, 80mm, 70 mm), Endpoint(350mm, 220 mm, 130 mm) made of aluminum extruded. and the two pipes were created for the pass of the fluid domain into the cold plate and the dimensions are as follow

Inlet pipe: thickness : 5mm, connected @ (100mm, 0 mm, 100mm) and radius 15 mm, the inlet water velocity is 0.2 m/s

Outlet pipe: thickness : 5mm, connected @ (300mm, 0 mm, 100mm) and radius 15 mm

Cold plate fluid block:

The cold plate Fluid block was created accordingly as per the given dimensions in the challenge with a start point (60 mm 90mm, 80 mm), Endpoint (340mm, 210 mm, 120mm)

Plates:

The cold plate solid block was created accordingly as per the given dimensions in the challenge with a start point

Plate 1: conducting thick 10mm, 200W, located at 60mm having dim (260 mm X 100 mm) in Z plane

Plate 2: conducting thick 10mm, 200W, located at 130mm having dim (260 mm X 100 mm) in Z plane

Cabinet opening:

Openings at the liquid inflow and outflow regions of the cold-plate are MinX and Max X

Final geometry:

We finally end up with the geometry as shown below after total set up.

Generate the Mesh:

Create a non-conformal mesh assembly:

Use mesh separately option with slack values:

Use object parameters:

Click Accept “change value" checks in the Mesh control panel and click on Generate mesh to mesh the model. Visualize the mesh at plane cuts and surface displays.

The mesh generation on the total solid domain in the geometry.

The mesh generation on the total fluid domain in the geometry.

The final mesh generation for the total domain including the solid and fluid together and the cut plane was in the z-axis

Setup:

Setting no of iterations and its convergence criteria:

The total number of iteration are 300 iterationns

Convergence criteria the flow is 0.00001

Joule heating energy is 1e-15,

Turbulent kinetic energy and turbulent dissipation rate are 0.001

Advanced solver setup:

Solve for Flow and Temperature and Radiation is off. The turbulence model is the Zero equation model:

Basic parameters and choose the Zero equation turbulence model for the flow regime in the General setup tab.

The heat-transfer due to the radiation is Ignore . The radiation parameter is also disapplied.

Set up the gravity vector:

Gravity acts in the negative x-direction in this problem. To set up the effects of gravity, toggle on the Gravity vector in the General setup tab. Enter the new values for the gravity vector as x = -9.80665, y = 0 and z =0. Now go to the Transient setup tab and set an initial velocity X velocity = 0.005 m/s in the x-direction.

Setup transient simulation with an initial velocity of 0.005 m/s in antigravity direction.

Set up monitor points in the model:

Save and Solve the model:

Post-processing and the results:

Residual plot:

From the residual plot provided above it is clear that the simulation has reached the converged stage and also obtained the convergence, and they are no fluctuations in the plot.

Temperature monitoring points:

The four monitor points to the Points folder, the four monitor temperatures are at the center of the opening.1 (outlet opening) opening-4 (Outlet), and at the center of block.2 and plate.2.From the above graph, it clearly shows that the obtained temperatures for the inlet temperature for the cabinet were at 25°C and the outlet temperature for the cabinet was at 20°C. The block-2 temperature was at 23°C and the plate-2 temperature was at 35°C

Plane cut:

Pressure contour representation for the cut-plane:

For the cut plane representation, we have shown the pressure contour on the z plane for the model.

Vector plot:

The Vector plot was set to the z plane through the plane and it is clearly seen that the inlet velocity for the opening was at the initial value of 0.02m/sec and a maximum velocity was at the value of 0.23m/sec was obtained in the domain and the velocity inside the sidewall domain was nearly at 0.145m/sec.

Temperature contour:

The Temperature Contour was set to position accordingly to the z plane through the plane and it is clearly seen that the inlet temperature for the opening was at the 20°C and a maximum temperature of 33.5°C was obtained in the domain and the temperature inside the solid domain was nearly at 30°C.

Velocity contour:

The Velocity Contour was set to position accordingly to the z plane through the plane and it is clearly seen that the inlet velocity for the opening was at the initial value of 0.02m/sec and a maximum velocity was at the value of 0.23m/sec was obtained in the domain and the velocity inside the sidewall domain was nearly at 0.145m/sec.

Object face:

Object face to display temperature contour on overall Cold-Plate Model:

The overall temperature distribution throughout the cold-plate model was shown in the above Figure.

Object face to display velocity contour on overall Cold-Plate Model:

The overall Pressure distribution throughout the cold-plate model was shown in the above Figure.

Conclusion:

A cold plate transient CHT using Icepak CFD simulation was performed seeing both an inner forced turbulent water flow and an external natural convection flow, generating a good quality non-conforming mesh using an assembly condition box and obtaining the postprocessing contours and vectors to see the effect of the system conditions.