Create: Thermal¶
Thermal fields are a specialized extension of the scalar field framework used to represent the evolution of temperature throughout the flow domain. Like scalar fields, thermal fields are single-valued quantities defined at each lattice location and evolve according to an advection–diffusion equation, solved in tandem with the fluid field.
The thermal field follows the same transport framework as scalar fields but represents temperature rather than species concentration. This allows temperature to be initialized, transported, and introduced through boundary conditions in a manner consistent with other transported quantities. The local temperature can be accessed within user-defined functions (UDFs) as an additional fluid variable.
Users specify the initial temperature, thermal diffusivity, and specific heat with optional inputs, such as the fluid expansion coefficient to model buoyancy effects. The local temperature may also be used in viscosity UDFs to capture temperature-dependent fluid behavior.
In addition to fluid-phased heat transfer, M-Star supports thermal conduction within static (solid) bodies and thermal contact resistance between adjacent solids. Conduction in static bodies is modeled as a purely diffusive transport process. Thermal contact resistance between static body families can be specified through user-defined contact resistance, enabling modeling of imperfect thermal interfaces and heat transfer limitations across material boundaries. Conjugate heat transfer is supported at fluid–solid interfaces, allowing users to capture the competition between convection in the fluid and conduction in the solid.
Representations
Thermal Field: Thermal fields are continuous field variables that evolve according to the advection–diffusion equation. They are used to model heating, cooling, and general thermal transport processes within the fluid. The thermal field can interact with particles via particle–thermal coupling, interfaces via interface–thermal coupling, and static bodies via appropriate boundary conditions.
Static Body Conduction: Static body conduction is used to model three-dimensional temperature distributions within solid bodies. This feature enables simulation of heat transfer within solids, where temperature evolution is governed by diffusion and controlled through initial and boundary conditions, including specified temperature or heat flux.
Thermal Contact: Thermal contact describes the interaction between two touching static bodies. It is used to model heat exchange between solids in imperfect contact. A user-defined contact resistance, combined with the local temperature difference, determines the heat flux across the interface.
Thermal Field Output
Thermal Output Data: The local temperature concentration can be exported during the simulation both as reduced statistical quantities and as spatial datasets for analysis and visualization. In addition, local/global heating rates and the temperatures at all inlets and outlets are recorded.