A non-zero value for resistivity should always be specified for solids in which Joule heating occurs. To simulate insulative (non-conductive) materials, apply a resistivty value that is 1000 times greater than the smallest specified resistivity. By default, such a material is considered to be an insulator, and is not thermally affected by electric current.
To simulate a resistivity that is greater than this default threshold, enable this flag, and specify the desired ratio. Joule heating is computed in solids with resistivity values that do not exceed this value.
For example, to compute Joule heating effects in a material that has a resistivity 10000 times greater than the smallest specified resistivity in the model, enable this flag, and assign a value of 10000.