A few definitions
Filling sand castings. Basic concepts

The most common system types include :

• a funnel or pouring basin;

• a vertical downspout with cross-sectional area S_d;

• a horizontal duct, known as the pouring channel, with cross-section S_c upstream of the first attack, distributing the metal flow into the cavity via small ducts, known as attacks, whose total cross-section is S_a .

Depending on whether the sequence of relative values of the cross-sections S_d, S_c and S_a is increasing or decreasing, it is common practice to say that the system is in negative pressure or in pressure.

These terms are not correct, as they do not always correspond to the reality of the flow phenomena that occur; it would be more accurate to say that this sequence of sections is simply diverging or converging.

If we...