﻿ Cooling of IC inside the Case by Natural Convection (Closed Space and Natural Convection Boundary Condition)Examples | Product | Murata Software Co., Ltd.

# Example10Cooling of IC inside the Case by Natural Convection (Closed Space and Natural Convection Boundary Condition)

### General

• Heat dissipation of the IC by the natural convection is solved by the steady-state analysis. The IC is encased on the substrate.

• The natural convection boundary condition is applied to the surface of the case to omit the analysis of open space outside the case. Only natural convection in the closed space inside the case is analyzed.

• In [Example 9: Cooling of IC inside the Case by Natural Convection (Closed Space and Open Space)], the same model is used and the natural convection in the open space is analyzed as well.
The outside of the case is analyzed in depth. Accordingly, the analysis time becomes longer.

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

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

### Analysis Space

 Item Setting Analysis Space 3D Model Unit mm

### Analysis Condition

 Item Setting Solver Fluid analysis [Bernoulli] Thermal analysis [Watt] Analysis Type Fluid analysis: Steady-state analysis Thermal analysis: Steady-state analysis Laminar Flow/Turbulent Flow Select Turbulent Flow Option Select Take Buoyancy into Account (Natural Convection) Layer Mesh Setting for Wall Surface (General Settings) Parameters for Automatic Creation Expected Temperature Difference: 50[deg] Meshing Setup General Mesh size: 5 [mm]

### Model

The substrate (VOL1), the IC (VOL2), and the case (CASE) are solid bodies.

The outer boundary condition is used. Natural convection (automatic calculation) is set for Heat Transfer: Convection.

Inside of the case (air) is a solid body.

### Setting of Body Attributes, Materials, and Mesh Sizes

 Body Number/Type Body Attribute Name Material Name Mesh Size 0/Solid VOL1 006_Glass_epoxy * 2.0 1/Solid VOL2 001_Alumina * 2.0 2/Solid Air 000_Air(*) – 3/Solid CASE 001_Al * 4.0

* Available from the material DB

IC (VOL2) is set as follows on the Heat Source tab.

 Body Attribute Name Tab Setting VOL2 Heat Source 1W

### Boundary Condition

 Boundary Condition Name/Topology Tab Boundary Condition Type Setting Outer Boundary Condition Fluid-Thermal Inlet/Outlet Natural Inflow/Outflow Inflow temperature: Use ambient temperature (25[deg]) Thermal Heat Transfer: Convection Room temperature (ambient temperature): 25[deg] Select Natural Convection (automatic calculation)

### Results

The temperature distributions of the substrate and IC are shown below.

The case and the air are hidden.

For comparison purpose, the results of
[Example 9: Cooling of IC inside the Case by Natural Convection (Closed Space and Open Space)] are shown as well where the outside of the case too is analyzed.

Similar results are obtained.

By switching the analysis type from thermal to fluid analysis, the flow velocity vectors are shown as below.

The cross section at x=0 is displayed.

In the graphics setup, the 3D vector is set OFF and the vectors are set to the same length.

Like the results of Example 9, the circulation is generated by the convection inside the case.

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