DTCHull fails on various number of domains in parallel

$FOAM_TUTORIALS/multiphase/interDyMFoam/ras/DTCHull run on centOS (vanilla 1612+ compiled with all default options).

runs fine on 16 and 32 CPUs

fails on 4 and 8 CPUs.

case on 4CPUs on k growing out of bounds: log_interDyMFoam_4

case on 8 CPUs suddenly with SigSev on pressure equation. log_interDyMFoam_8

See logs attached.