heat transfer between the air in the cavity and the surrounding solid layers

I am working on simulating heat transfer in a component that consists of multiple solid layers and an enclosed air cavity using the PDE Toolbox in MATLAB. My goal is to account for heat transfer mechanisms such as radiation and convection between the air in the cavity and the surrounding solid layers. is this possible with the pde toolbox? Is there a solutuion without modelling the air as a solid material?

[Torsten]

What would be the heat transfer model you want to solve with the PDE toolbox ? Free convection in the cavity ? Radiation between the air and the walls of the cavity depending on the distance to the wall ? Conduction in the solid layers ?

In this case, you will have to use a CFD program, preferably ANSYS.

Answer 1

[Rahul]

Hi @Patrick Frey,

In order to achieve the desired result you can use of the 'thermalProperties' and 'thermalBC' functions according to the specific requirements of your heat transfer component.

In your model you can define multiple 'termalProperties' with respect to either solid or the air cavity.

% To define Thermal properties for the solid layers
thermalProperties(model, 'ThermalConductivity', 200, 'MassDensity', 7800, 'SpecificHeat', 500, 'Face', [1, 2]);

% To define Thermal properties for the air cavity 
thermalProperties(model, 'ThermalConductivity', 0.026, 'MassDensity', 1.225, 'SpecificHeat', 1005, 'Face', 3);

% The values of individual properties are just added for your reference, you can change them accordingly. 

The 'Face' property available would allow to assign these properties to different components of the model.

Using the 'thermalBC' function you can set the boudary conditions needed for the heat transfer in the air cavity.

% Boundary condition for convection can be set using the 'ConvectionCoefficient' property
h = 10; 
Tinf = 300;
thermalBC(model, 'Edge', [3, 4, 7, 8], 'ConvectionCoefficient', h, 'AmbientTemperature', Tinf);

% Boundary condtion for radiation can be set using the 'Emissivity' property
emissivity = 0.8;
thermalBC(model, 'Edge', [3, 4, 7, 8], 'Emissivity', emissivity, 'AmbientTemperature', Tinf);

% The values of individual properties are just added for your reference, you can change them accordingly. 

You can refer to the following documentations to know more about these functions:

'thermalProperties' - https://www.mathworks.com/help/releases/R2024a/pde/ug/pde.thermalmodel.thermalproperties.html?searchHighlight=thermalProperties&s_tid=doc_srchtitle

'thermalBC' - https://www.mathworks.com/help/releases/R2024a/pde/ug/pde.thermalmodel.thermalbc.html?searchHighlight=thermalBC&s_tid=doc_srchtitle#d126e144300

Hope this helps. Thanks!