Level of Initial Mesh

The Level of initial mesh governs the mean number of cells (Nmean) per the model’s middle size (Hmean) and the number of cells (Ngap) per the smallest flow passage/channel height, which specified by the Minimum gap size value (hgap).

First of all, the geometry resolution coefficient (Kres) is defined as the ratio of the model’s middle size (Hmean) to the minimum gap size (hgap). If it is smaller than 2.5, the number of cells per the model size (Nmean) and the number of cells per the minimum gap size (Ngap) are specified by using the table below. Note, that the real number of cells per a gap is restricted by the maximum allowed channel refinement level (L*ch).

Table 1. APD mesh settings.
Level of initial mesh	Nmean			Ngap	L*ch
	Internal	External
	Internal	Incompressible	Compressible
1	5	2	3	2	0
2	7	3	5	3	1
3	10	5	7	5	2
4	14	7	10	7	2
5	20	10	14	10	2
6	28	14	20	14	4
7	40	20	28	20	4

See Table 2 illustrating how the APD technology works.

Table 2. APD technology example.
a) Lini = 4; hgap = 18 mm	b) Lini = 4; hgap = 4 mm

If Kres is greater than 2.5, the Nmean value is multiplied by the normalized coefficient Knorm depended on the Kres. Also in these cases the maximum allowed channel refinement level (L*ch) cannot provide a sufficient number of cells per a gap. So if the Kres >> 1, it is recommended to enable the Advanced channel refinement option.