Home / Examples / Thermal Analysis [Watt] / Example 7: Heat Radiation by Forced Convection (Steady-State Analysis)

Example 7: Heat Radiation by Forced Convection (Steady-State Analysis)

General

• A heat source is placed on a substrate, and there is a forced air flow for cooling in parallel to the substrate. The heat radiation is analyzed under the steady-state condition.
   

• The heat transfer coefficient is acquired manually.
  To acquire it automatically, see "Ex.1 of Simple Fluid-Thermal Analysis".
   

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

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




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

Analysis Space

Analysis Conditions

Model

The substrate (VOL1) and the heat source (VOL2) are created as solid bodies, and the heat amount is defined in the body attribute of VOL2.

The heat transfer coefficients for the top and bottom faces of the substrate and the top face of the heat source are calculated by the simplified equation and set to them.

Body Attributes and Materials

* Available from the material DB

The heat source of VOL2 is set up as follows.

Boundary Conditions

The heat transfer coefficients for the forced convection are calculated as follows. See [Heat Transfer Coefficient for Forced Convection] for more information.

To acquire it automatically, see [Ex.1 of Simple Fluid-Thermal Analysis].
 

h = 3.86 x (V/L)0.5 x C [W/m2/deg]

where

Air flow V=1 [m/s]

Top and Bottom Faces of Substrate (VOL1): Typical length L=0.05, C=1 -> h=17.26
Top Face of Heat Source (VOL2): Typical length L=0.02, L'=0.015, C=1 * -> h=27.3

*

The thickness (d) of the speed boundary layer at the edges of the heat source is calculated as follows

δ=0.0182 x (L’/V)0.5= 2.3 [mm]

This is close enough to the thickness of heat source, so we set C=1.

Results

The temperature distribution is shown below.

A cross section's temperature distribution is shown below.