12. Potential Flow

Material properties for general flow elements -- applied in heat flow, concentration flow or fully saturated groundwater flow analysis -- can be constant or they can depend on a variable like temperature, concentration, potential, time, or degree of reaction. The preliminary analysis needs the constant properties, so you must always input these, even if you intend to perform a nonlinear or transient analysis only.

Constant material properties are compulsory input for a preliminary or linear analysis. Variable material properties may be additional input for a nonlinear or a transient analysis.

Variable properties.

User specified functions for variable material properties are input by multi-linear diagrams.

If the material properties depend on one variable, you must specify points in a two-dimensional diagram: a set of values for the variable and a set of corresponding values for the material property. If the material properties depend on two variables, you must specify points in a three-dimensional diagram: for each successive point on the axis for the first variable, you must specify the values of the property for all points on the axis for the second variable. During the analysis, DIANA determines the current value for the material properties by linear interpolation in the diagram that you specified.