Field Functions

The following field functions are made available to the electronics cooling simulation depending on the physics setup:

Scalar Field Functions

Boundary Emissivity (requires radiation): The gray emissivity at a surface.
Boundary Emissivity on External Side (requires radiation): The gray emissivity at the surface for the outward facing side. This field function only available on outer wall surfaces if external radiation is enabled.
Boundary Heat Flux: The magnitude of the heat flux vector normal to the surface. It is defined as $(\dot{q} ″ \cdot a) / | a |$ .
Boundary Heat Flux on External Side: The magnitude of the heat flux vector normal to the surface for the outward facing side. This field function is only available on outer wall surfaces if external radiation is enabled.
Boundary Heat Transfer: The heat transferred at the surface, defined as $\dot{q} ″ \cdot a$ .
Boundary Irradiation (requires radiation): The irradiation at the surface. The irradiation is the radiative heat flux incident on a surface.
Boundary Irradiation on External Side (requires radiation): The irradiation at the surface for the outward facing side. This field function is only available on outer wall surfaces if external radiation is enabled.
Boundary Radiation Heat Flux (requires radiation): The net radiative heat flux to the surface (absorption minus emission). A positive value indicates a net absorption by the boundary.
Boundary Radiation Heat Flux on External Side (requires radiation): The net radiative heat flux for the outward facing side. This field function is only available on outer wall surfaces if external radiation is enabled.
Cell Quality: Cell quality is a function that is determined from the relative geometric distribution of the cell centroids of the face neighbor cells and of the orientation of the cell faces. Generally, flat cells with highly non-orthogonal faces have a low cell quality. A cell with a quality of 1.0 is considered perfect. A degenerate cell has a cell quality approaching 0. Depending on the physics that you select, the cell quality of a cell can be fairly low and still provide a valid solution. However, poor cell quality is likely to affect both the robustness and accuracy of the solution.
Density: The material density defined by the method that you chose for the Setup.
Effective Viscosity: The sum of the laminar and turbulent viscosities $μ + μ_{t}$ .
External Ambient Temperature: The surface ambient temperature that you specify on a wall surface. This field function is only available on outer wall surfaces if the Thermal Specification is set to Convection.
External Heat Transfer Coefficient: The surface external heat transfer coefficient that you specify on a wall surface. This field function is only available on outer wall surfaces if the Thermal Specification is set to Convection.
Heat Transfer Coefficient: The wall boundary heat transfer coefficient defined by:
$h = ({\dot{q} ″}_{c o n d u c t i o n} \cdot a) / [| a | (T_{ref} - T_{f})]$
where $T_{f}$ is the wall boundary temperature and $T_{ref}$ is the specified reference temperature in the field function.
Mass Flow Rate: The rate at which mass flows through an open surface.
Static Pressure: The spherical part of the stress tensor acting in fluids, which is the same as the actual thermodynamic pressure of the fluid. When the gravity model is active, it is related to the working pressure, (which becomes the piezometric pressure), by Eqn. (946) for variable density flows and by Eqn. (950) for constant density flows.
Temperature: The temperature field.
Thermal Conductivity: The thermal conductivity material property according to the method that you defined for the physics. This field function is a scalar value and therefore not populated in regions where thermal conductivity is defined by an anisotropic tensor.
Total Pressure: The total pressure (gauge) is the pressure that is obtained from isentropically bringing the flow to rest. For an ideal gas with constant specific heat, it is defined as
$P_{t} = P_{abs} [{(1 + \frac{(γ - 1)}{2} M^{2})}^{γ / (γ - 1)}] - P_{ref}$
where $P_{abs}$ , $P_{ref}$ , $M$ and $γ$ are the absolute pressure, reference pressure, Mach number, and ratio of specific heats, respectively. For alternate equations of state, or a non-constant specific heat, $P_{t}$ is obtained by integrating $d h = d P / ρ$ from static conditions to total conditions.
Turbulent Dissipation Rate: The transported variable $ε$ in the K-Epsilon Turbulence model.
Turbulent Kinetic Energy: The transported variable $k$ in the K-Epsilon Turbulence model.
Turbulent Viscosity: The turbulent viscosity $μ_{t}$ in the K-Epsilon Turbulence model. The K-Epsilon Turbulence model belongs to the family of Eddy Viscosity Models and therefore uses the concept of a turbulent viscosity to model the Reynolds stress tensor as a function of mean flow quantities.
Velocity: Component n (where n = 0, 1, 2): The velocity component in x, y, or z direction respectively.
Velocity: Magnitude: The magnitude of the Velocity vector.
Vorticity: Magnitude: The magnitude of the Vorticity vector.
Wall Shear Stress: Magnitude: The magnitude of the Wall Shear Stress vector.

Vector Field Functions

Area: The vector of the face area components, that is the area magnitude multiplied by the unit normal. You can also run the Area field function on an unmeshed surface.
Velocity: The velocity vector field.
Vorticity: The vector variable with components $ζ_{x}$ , $ζ_{y}$ , $ζ_{z}$ defined as:  
$ζ_{x} = \frac{\partial w}{\partial y} - \frac{\partial v}{\partial z}, ζ_{y} = \frac{\partial u}{\partial z} - \frac{\partial w}{\partial x}, ζ_{z} = \frac{\partial v}{\partial x} - \frac{\partial u}{\partial y}$
  where $u$ , $v$ and $w$ are velocity components in the x, y and z directions. $\nabla\times v$ is the curl of the velocity field.
Wall Shear Stress: The wall shear stress vector, which is defined at a wall face as ${\overset{⇀}{τ}}_{w} = (- T \cdot a / | a |)$ , where $T$ is the stress tensor and $a$ is the Area vector.