# 3D Example: Conduction Heating with Multiphysics

## Foreword

This paragraph is a summary of cases treated in detail in the technical document: " 3D Conduction Heating with Multiphysics Technical Paper ".

The files relating to the studied cases, are accessible in the supervisor on the Open example context.

## Studied device

The device to be analyzed is a micro gas sensor (heating circuit).

The studied device, represented in the figure below, includes the following elements:

• heating element in platinium (electrode):
• thickness: 10 μm
• substrate of oxidized silicium:
• thickness of Si: 200 μm
• tickness of SiO2: 0.06 µm

## Operating principle

The heating element – electrode – is supplied by a voltage source (1V).

We are interested in the temperature distribution in the plate.

## Electric problem

The electric problem is briefly summarized below.

• Geometry: The study domain contains only the electrode (the silicon substrate, the thin silicon oxide layer and the air are insulating regions that are not modeled).

• Mesh: Mapped mesh at the base faces and extrusive mesh in thickness.

• Physical properties:

## Thermal problem

The thermal problem is briefly summarized below.

• Geometry: The study domain contains the electrode, the substrate of silicon and the layer of silicon oxide (the surrounding air is not included).
• Mesh: Automatic mesh at the base faces and extrusive mesh in thickness.

• Physical properties:

At this stage of the description, there is no heat source for the thermal problem.

## Source

The source of heat is the current flowing through the electrode.

## Studied case

Three studies are demonstrated:

• study 1: single sequence between the Electric Conduction application and the Steady State Thermal application
• study 2: multiphysics coupling between the Electric Conduction application and the Steady State Thermal application
• study 3: multiphysics coupling between the Electric Conduction application and the Transient Thermal application

## Study 1

Physical phenomena are considered independent – the thermal variations of the electric resistivity of platinum are not taken into consideration.

## Study 2

Physical phenomena are considered interdependent – the thermal variations of the electric resistivity of platinum are taken into consideration.

## Study 3

Physical phenomena are considered interdependent – the thermal variations of the electric resistivity of platinum are taken into consideration. The thermal application is transient.