srd velocity scaling

Please post to the list, not to me.

From the manual:

Lamda cannot be smaller than 0.6 * hgrid, else an error is generated
(unless the {shift} keyword is used, see below). The velocities of
SRD particles are bounded by Vmax, which is set so that an SRD
particle will not advect further than Dmax = 4*lamda in dt_SRD. This
means that roughly speaking, Dmax should not be larger than a big
particle diameter, else SRDs may pass thru big particles without
colliding. A warning is generated if this is the case.

So Vmax is a function of the timestep you choose. If you
want a larger Vmax, you need to choose a smaller timestep.
It’s really a distance constraint. You can’t allow particles
to move too far in one timestep.