Adiabatic Heating
Add an Adiabatic Heating node to model abrupt changes in temperature due to fast deformation. The increase in temperature is then defined by solving the distributed equation
here, ρ is the density, Cp is the heat capacity at constant pressure, T is the temperature field, βah is the coefficient of adiabatic heating, and Qh corresponds to the heat sources due to mechanical dissipative processes.
The Adiabatic Heating node is only available with some COMSOL products (see https://www.comsol.com/products/specifications/).
Initial Values
Enter the Initial temperature Tini. The default value is 293.15 K.
Thermodynamics
The density ρ is taken from the material model (Linear Elastic Material, Nonlinear Elastic Material, or Hyperelastic Material).
The default Heat capacity at constant pressure Cp uses values From material. For User defined, enter an expression or value. The default value for the User defined is J/(kg K).
Enter the Coefficient of adiabatic heating, βah. The default value is 1 (dimensionless), which means that dissipative processes contribute 100% as heat sources.
Select the Dissipative heat sourceInclude all dissipative sources or User defined.
The Dissipative heat source list makes it possible to include specific heat sources for the adiabatic heating. Enter a value or expression for the heat source Qh to include. For instance, the dissipated energy density due to creep is available under the variable solid.Wc and due to viscoplasticity under the variable solid.Wvp. Here solid denotes the name of the physics interface node.
Time Stepping
Select a MethodAutomatic, Backward Euler, or Domain ODEs.
The Backward Euler method is not available with the Layered Shell interface nor with the Layered Linear Elastic Material in the Shell and Membrane interfaces.
Automatic
The Automatic method corresponds to the backward Euler method except for the Layered Shell interface or when the Layered Linear Elastic Material is used. Domain ODEs are solved in these cases.
Backward Euler
For the Backward Euler method, enter the following settings:
Maximum number of local iterations. To determine the maximum number of iteration in the Newton loop when solving the local equation.
Absolute tolerance. To check the convergence of the local equation based on the step size in the Newton loop.
Relative tolerance. To check the convergence of the local equation based on the step size in the Newton loop. The final tolerance is computed based on the current solution of the local variable and the entered value.
Residual tolerance. To check the convergence of the local equation based on the residual.
If both a step size and residual convergence check is requested, it is sufficient that one of the conditions is fulfilled. Setting either the Absolute tolerance and Relative tolerance or the Residual tolerance to zero ignores the corresponding convergence check. An error is returned if all are set to zero.
Domain ODEs
No settings are needed for the Domain ODEs method. However, this method adds degrees-of-freedom that are solved as part of the general solver sequence. The scaling of this field can affect the convergence of the overall solution.
Location in User Interface
Context Menus
Ribbon
Physics tab with Solid Mechanics or Membrane selected: