In order to avoid injection molding, it is necessary to know the places with a large cross-section and apertures. There must be provisioned nodes called dead heads. Their purpose is to feed the metal with the casting until it stops. Insects are formed in the dead heads.
To calculate sprue height in sand casting process. You need to define the riser design: if the riser is side riser, in the case and the riser neck in the parting line so in this case the sprue height= the riser height.
if the riser is designed to be top riser: the sprue height = riser height+ the part of thickness of cast in cope.
Stream optimization (speed increase) is accomplished by altering the geometry by height, changing the cuts and gradients along the height of the column.
Congratulations on scientific work and creative success.