**Case Studies**** > Multiphysics**

**Case List**

__Case 1: Thermo-Mechanical analysis of Motherboard__

Case 2: Thermo-Flow analysis of Motherboard

Case 3: Thermo-Mechanical analysis of Heating Circuit

Case 4: Thermo-Mechanical analysis of Heating Transistor

Case 2: Thermo-Flow analysis of Motherboard

Case 3: Thermo-Mechanical analysis of Heating Circuit

Case 4: Thermo-Mechanical analysis of Heating Transistor

**Case 1: **Thermo-Mechanical analysis of **Motherboard**

This model is to simulate heat effect in a motherboard using COMSOL Multiphysics. Three physics types are included in this coupling analysis: Solid Mechanics, Heat Transfer in Solids, and Multiphysics. Two linear heat sources and one general heat source are defined to the 4 cylindrical parts and 2 cubes. All the surfaces marked in blue are defined with convective heat flux.

The whole mode is meshed with tetrahedral elements using "Finer" mesh option. The six joints are represented by rigid connectors with fixed constraints in each center. The simulated results of surface temperature, isosurface temperature and stress are predicted.

The whole mode is meshed with tetrahedral elements using "Finer" mesh option. The six joints are represented by rigid connectors with fixed constraints in each center. The simulated results of surface temperature, isosurface temperature and stress are predicted.

Fig. 1-5 Temperature isosurface

**Case 2: **Thermo-Flow analysis of **Motherboard**

This example models the cooling characteristics of motherboard. "Heat Transfer" including solid and fluid and "Laminar Flow" are coupled in the multiphysics simulation. The whole mode is meshed with tetrahedral elements using "Normal" mesh option.

## Case 3: Thermo-Mechanical analysis of Heating Circuit

This model shows simulation of circuit heating process. The circuit with a thickness of 10 µm is represented by membrane element and is assigned with a boundary heat resource. Heat flux conditions are set up on the top and bottom surfaces of the plate. The coupling analysis is executed with "Solid Mechanics", "Heat Transfer in Solids", "Membrane" and "Multiphysics".

The distribution of stress, temperature, and isosurface temperature are predicted.

The distribution of stress, temperature, and isosurface temperature are predicted.

## Case 4: Thermo-Mechanical analysis of Heating Transistor

Thermal stress effects of a heating transistor is simulated by coupling "heat transfer" and "structural mechanics" analysis types.

A convective heat flux with a heat transfer coefficient of 10 [W/m^2/K] is assigned to all the surfaces. The cylindrical block provides a linear heat source with a value of 5000 [W/m^3/K]. The 4 bolts are represented by 4 rigid connectors with fixed constraints to simplify the models. Tetrahedral elements are meshed for the whole model.

The temperature distribution and stress distribution are predicted.

A convective heat flux with a heat transfer coefficient of 10 [W/m^2/K] is assigned to all the surfaces. The cylindrical block provides a linear heat source with a value of 5000 [W/m^3/K]. The 4 bolts are represented by 4 rigid connectors with fixed constraints to simplify the models. Tetrahedral elements are meshed for the whole model.

The temperature distribution and stress distribution are predicted.