Coupled thermal and flow analysis of a power supply

1: Open the Simulation file

On your desktop or the appropriate network drive, create a folder named power_supply.

Click the link below:

Download the part

Extract the part files to your power_supply folder.
Start Simcenter 3D or NX.

File

Open

Look in

power_supply

Files of type

Simulation Files (*.sim)

File name

power_supply.sim

OK

2: Reset dialog box memory

The options you select in dialog boxes are preserved for the next time you open the same dialog box within a given session. Restore the default settings to ensure that the dialog boxes are in the expected initial state for each step of the activity.

File

Preferences→User Interface

Options

Reset Dialog Memory

OK

3: Explore the FEM and Simulation files

The FEM file has already defined:

Meshes
Mesh collectors with all material and physical properties

Simulation Navigator

power_supply_fem.fem→3D Collectors
Input_Filter_Capacitor_2_Collector
Information
Information window
Explore the mesh collector definition and the FEM structure.

Several boundary conditions are already created for you, including heat transfer coefficient thermal couplings, and heat loads.

The default method for defining boundary conditions in Simcenter 3D Thermal/Flow or Simcenter 3D Electronic Systems Cooling (ESC) is to apply the boundary condition on the model geometry rather than on the mesh. The software resolves the associated elements during the analysis. However, if geometry is not available, you can define boundary conditions on the elements as well.

Simulation Navigator

Simulation Object Container
Side Vents
Information
Information window
Explore other loads, thermal couplings and boundary conditions.

4: Create a thermal coupling

To complete the model thermal connections, add a thermal coupling between the contacting surfaces of the first input filter capacitor and the printed circuit board.

(1) input filter capacitor and (2) printed circuit board

Simulation Navigator

Polygon Geometry
Air_Volume (58) (hide)

View

See-Thru All (Visibility group)

Home

Thermal Coupling (Loads and Conditions group→ Simulation Object Type list)

Name

Input_Filter_Capacitor_1_to_PCB

(Primary Region)

Select the bottom face of the capacitor. You may need to use QuickPick to make the selection.

Secondary Region

Secondary Region (Select Object)
Select the top face of the circuit board. You may need to use QuickPick to make the selection.

Assume the following: the capacitor not only has its connections welded to the PCB; it was also glued using a thermal adhesive of thermal conductivity k=7 W/m°C; a 1 mm gap exists between the PCB and the board.
The heat transfer coefficient would be: 7000 W/m²°C

Type

Heat Transfer Coefficient

Coefficient

7000 W/(m²·°C)

OK

View

See-Thru All (Visibility group)

5: Create the outlet fan

Create an outlet flow boundary condition to model an outlet fan with a predefined curve. To specify the fan curve, use the provided data points text file.

Simulation Navigator

Air_Volume (58) (show)

Home

Flow Boundary Condition (Loads and Conditions group→ Simulation Object Type list)

Type

Outlet Flow

Name

Commercial_fan

Select the circular face that represents the fan opening.

Magnitude

Mode

Fan Curve

(Fan Curve)
New Field→Table

Data Points

Import from Text File

File Browser

power_supply_fan_curve.txt

OK

Table Data Import window

OK

Table Field dialog box

(Fan Curve)
Plot(XY)
Create New Window (Viewport dialog box)
Graph Window 1 dialog box

OK

Flow Boundary Condition dialog box

6: Create the opening boundary condition

Create an opening flow boundary condition to provide an entry for the air.

Flow Boundary Condition (Loads and Conditions group→ Simulation Object Type list)

Type

Opening

Name

Rear_Vent

Select the face on the side of the power supply opposite the fan.

Head Loss

Head Loss_1

Note:

This modeling object was predefined for you in the Simulation file. It defines a head loss coefficient of 0.25 that is proportional to dynamic pressure.

OK

7: Create a heat load

A heat load defines the power the selected geometry has. Create a 3 W heat load to simulate heat generated from the first input filter capacitor.

Thermal Loads (Loads and Conditions group→ Load Type list)

Type

Heat Load

Name

Input_Filter_Capacitor_1_3W

Type Filter (Top Border bar)

Polygon Body

Select the Input_Filter_Capacitor_1 polygon body.

Heat Load

3 W

OK

8: Solve the model

The model should solve under 10 minutes.

Simulation Navigator

power_supply_coupled_solution
Solve

OK

Wait for Completed to display in the Analysis Job Monitor dialog box, before proceeding.

Yes

Review Results dialog box

Review the messages in the Solution Monitor dialog box.
Solution Monitor dialog box
the Information window

Cancel

Analysis Job Monitor dialog box

9: Display the elemental temperature results

Post Processing Navigator

Thermal-Flow
Load
Thermal-Flow
New Post View→Contour
Note:

Notice the temperatures in the color bar vary approximately between 28 – 63 °C.
Feature (Display group→Edge Style list)
Post View 1
Annotations (show)
Note the minimum and maximum temperatures.
Annotations (hide)