Home / Examples / Coupled Analysis / Fluid-Thermal Analysis [Bernoulli/Watt] / Example 14: Cooling by Fan

Example 14: Cooling by Fan

General

• A heat source is placed inside the case. A fan on the case cools the heat source.
   

• The fan pressure and the flow rate are determined according to the pressure loss. The operating point of the fan can be output as well.
  

• The monitoring values are used for convergence judgment.
  

• The temperature distribution and the heat flux vectors are solved.
  

• The results can be viewed by the simultaneous display of temperature contours and streamlines.
   

• Unless specified in the list below, the default conditions will be applied.
   

• Obtain this session's project file. (Right-click and choose 'Save link as')




• Results will vary depending on Femtet version and the PC environment.

 

Analysis Space

Item	Settings
Analysis Space	3D
Model Unit	m

 

Analysis Conditions

Item	Setting
Solver	Fluid Analysis [Bernoulli] Thermal Analysis [Watt]
Analysis Type	Steady-state Analysis
Flow Type	Select External Flow.
Detailed Setting	Convergence Judgment by Monitoring Value Enable

 

 

Tab	Monitoring Quantity	Settings
Monitoring	Temperature	Monitoring Domain: Select [Body Attribute] Monitoring Value: Select [Maximum Value] Body Attribute Name: Select [All Body Attributes] Then click [Add].
	Volumetric Flow Rate	Monitoring Domain: Select [Body Attribute] Body Attribute Name: Select [Fan] Then click [Add].

 

Model

The heat dissipation of the heat source inside the case is calculated.

A fan and a vent are set on the case.

 

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Material Name
3/Solid	Source	Si
5/Solid	Case	001_Al *
6/Solid	Fan	000_Air *
7/Solid	Air	000_Air *

* Available from the material DB

 

 

Body Attribute Name	Tab	Setting
Fan	Fluid	Inflow and Outflow Faces are set to the both sides of the circular model.   Fluid Body Type: Specify flow Inlet/Outlet Type: Fan P-Q Characteristics Number Volumetric Flow Rate (Q) [m3/s] Differential Pressure (P) [Pa] 1 0 30 2 0.2 0

 

Boundary Condition

Set the inlet/outlet type of the outer boundary condition to natural inflow/outflow.

Since the temperature of the incoming fluid is the ambient temperature, the ambient temperature is applied In the [Ambient Setting] dialog box.

 

Results

The calculation was terminated by the monitoring values for convergence judgment before the residual converges.

 

Below are the transitions of the volumetric flow rate of the fan and the maximum temperatures of each body attribute that are predetermined as monitoring values.

(Displayable by clicking Check Convergence Status button in the dialog box after the analysis finishes)

Since the results are almost constant, it can be interpreted to be acceptable to terminate the calculation before the residual fully converges.

 

 

The figure below shows the streamlines and the contours of temperature distribution of the heat source at the same time. The contour field of the case is hidden.

The air flows into the case from the vent and flows out through the fan.

 

 

 

The operating point of the fan can be viewed in the result table.

 

 

By displaying on the graph, the operating point can be located on the P-Q characteristic.