Resistance

The

Resistance QuickPart does not resolve the internal structure of the component but uses a Porous Medium approach to describe the effect of the component on the overall flow and heat transfer. With this approach, you can model complex power supplies without considering geometric details. It is particularly useful for modeling PCB racks.

The Electronics Cooling Toolset supports the following simple shape templates:


Block	Cylinder

If none of the built-in shape templates are suitable, you can define a Custom resistance whose geometry is based on a Construction Geometry that you specify.

Note	The fluid that is contained in a Resistance QuickPart is the Default Gas material that you specify in the Setup panel. Resistance QuickParts are currently not supported in liquid domains.

Resistance—Properties

The following properties are common to all resistance types:


Name	Specifies the name of the resistance under which it is stored in the tree.
Geometry	Local Origin Specifies the position of the resistance's local coordinate system. See X_or, Y_or, Z_or in the Graphics window. It is used for placing the resistance in the simulation domain. The following options are available: Bottom Center: Center of the Zmin face. Bottom Corner 1 (block resistance only): Xmin/Ymin/Zmin corner of the block. Bottom Corner 2 (block resistance only): Xmin/Ymax/Zmin corner of the block. Center: Center of the geometry. Custom: This value appears when you set the local origin interactively within the Graphics window, see Placing Object Interactively.
Placement	See Placement properties.
Physics	Specifies the properties of a porous medium that is used to mimic the effect of the actual component on the overall flow and heat transfer. The Porous Inertial Resistance, the Porous Viscous Resistance, and the Solid Thermal Conductivity require the input of an XX Component, a YY Component, and a ZZ Component that represent the diagonal components of a Principal Tensor in the local coordinate system of the resistance. See X_or, Y_or, Z_or in the Graphics window. Porous Inertial Resistance, Porous Viscous Resistance Specifies the inertial and porous resistance of modeled component, respectively. For more detail, see Superficial Velocity Formulation. Porosity Specifies the ratio of open volume to total volume within the modeled component. Solid Thermal Conductivity Specifies the thermal conductivity of the modeled component. For more detail, see Solid Thermal Conductivity. Heat Source Specifies the total heat that the modeled component generates.

The following properties characterize the various resistance types:

Block—Specific Properties


Geometry	X, Y, Z Specifies the total size of the block in x-, y- and z-direction, in the resistance's local coordinate system. See X_or, Y_or, Z_or in the Graphics window.

Cylinder—Specific Properties


Geometry	Radius Specifies the radius of the cylinder. Height Specifies the extent of the cylinder from bottom to top.

Custom—Specific Properties


Geometry	Selected Construction Geometry Specifies the Construction Geometry that describes the resistance. If you select multiple Construction Geometries when creating a Custom resistance, the Electronics Cooling Toolset automatically creates multiple Custom resistance QuickParts that own the same physics.