/SPHGLO

Block Format Keyword

/SPHGLO - SPH Global Parameters

Description

Describes the SPH global parameters.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/SPHGLO
		Maxsph	Lneigh	Nneigh

Field	Contents
	Security coefficient on search for neighbors, so that for each particle more than the actual neighbors are found. This allows reducing the computational time. Maximum value is set to 0.5 Default = 0.25 (Real)
Maxsph	Maximum number of ghost particles allowed to be created at one time. It is used to allocate memory for ghost particles creation. (Integer)
Lneigh	Maximum number of neighbors to be taken into account for the SPH approximation. Default = 120, if Nneigh = 0 otherwise, = max(120,Nneigh) (Integer)
Nneigh	Maximum number of neighbors Default = 120 (Integer)

1.	Nevertheless, the number of neighbors found within the security distance should not be too large.

It is recommended to set the value of , so that neighbors next to the neighbors lying at distance 2h into the initial net will be retained (where h is the smoothing length defined into property).

This leads to =0.25 (default value), if the net is an hexagonal net and h is the minimum distance between two particles into the net.

2.	"Maxsph" default’s value is the number of SPH symmetry conditions multiplied by the number of particles, which corresponds to the case of all particles are symetrized with respect to each conditions and is sufficient to treat any problem.

3.	It is recommended to use the default value for "Maxsph".

Nevertheless, all particles do not generally need to be symetrized with respect to each condition and "Maxsph" default’s value can lead in specific cases to a large over-estimation of the necessary memory (refer to Maximum Number of Ghost Particles to be Created).

4.	"Nneigh" is the maximum number of neighbors to be stored around each particle.

It determines the memory allowed for storing the neighbors within the security distance at each bucket sort (refer to Maximum Number of Neighbors to be Stored).

5.	“Lneigh” determines the maximum number of particles participating to the SPH approximation around each particle. Thus, the number of particles participating to the SPH approximation around a particle, generally depends on the particle diameter h, but is limited to “Lneigh”.

6.	If “Nneigh” is less than 120, “Nneigh” is set to 120. If “Nneigh” is not equal to 0 and less than “Lneigh”, “Nneigh” is set to “Lneigh”.

7.	Setting Nneigh > Lneigh enables reducing the frequency of particles sorting.