with gas combustion, pulverised coal or the electric module, srrom is the sub-relaxation coefficient for the density, following the formula:
hence, with a zero value, there is no sub-relaxation. With combustion and pulversied coal, srrom is initialised to -grand and the user must specify a proper value through the Interface or the initialisation subroutines (usd3p1, usebu1, uslwc1, uscpi1 or uscpl1). With the electric module, srrom is initialised in to 0 and may be modified by the user in useli1. With gas combustion, pulverised coal or electric arcs, ssrom is automatically used after the second time-step. With Joule effect, the user decides whether or not it will be used in uselph from the coding law giving the density.
Always useful with gas combustion, pulverized coal or the electric module.