Card 7 - Element Merging and Renumbering

This optional card specifies element merging and renumbering by the MEREL module.

Parameters:


Option 1 element list maximum 13 elements per card	`M`, `NN2`, `NN3`, `NN4`,...
Option 2 maximum 2 group names	`NAME1`, `NAME2`
Option 3 single group name	`NAME1`
Option 4 element + group name	`NM`, `NAME2`
Option 5 group name + element	`NAME1`, `NN2`
Option 6 element generation	`GENER`, `N1S`, `INC1`, `N1N`, `INC2`, `N2N`

Code example

 10, 4, 5               
 $ ELEMENTS 4 AND 5 MERGED INTO ELEMENT 10
 GENER, 201, 1, 3, 10, 3
 $ ELEMENTS 202 AND 203 MERGED INTO 201
 $ ELEMENTS 212 AND 213 MERGED INTO 211
 $ ELEMENTS 222 AND 223 MERGED INTO 221
 BOX1,BOX2              
 $ ELEMS ASSOCIATED WITH CARD 9 NAMES BOX1
 $ AND BOX2 ARE MERGED INTO THE STARTING
 $ ELEMENT OF BOX1

Notes

Element merging/renumbering by the MEREL module consists of assigning one or more elements the element number of the starting element and automatically combining their conductances, capacitances, and heat loads. The resulting temperature will be the average of the merged elements.

Element merging should be used only if the elements are closely coupled, or are expected to have similar temperatures.

Element merging can reduce solution time by reducing the size of the model, and by eliminating high conductances that cause ill–conditioning.

For Option 1 elements NN2, NN3, NN4,... are merged into element NM.

For Options 2, NAME1 and NAME2 are group names and NM and NN2 are element numbers. NAME1 may not start with the letter C.

For Options 2, 3, and 5 the elements of NAME1 and NAME2 are merged with the starting element of NAME1. The starting element is the first element defined on the Card 9 group name NAME Card, or, for Simcenter 3D models, the lowest element number defined.

For Option 4 all the elements are merged into element NM.

Option 6 generates N2N Option 1 format Cards, each with N1N elements:


 N1S, N1S+INC1,....N1S+(N1N–1)INC1
 
 N1S+INC2, N1S+INC2+INC1,...N1S+INC2+(N1N–1)INC1
 
 N1S+(N2N–1)INC2,N1S+INC1+(N2N–1)INC2,..N1S+(N1N–1)INC1+(N2N–1)INC2

INC1 is the element number increment between the elements on the same line (between elements to be merged).

N1N is the number of elements in each line (maximum 13).

INC2 is the element number increment between the generated Cards (increment between elements to be merged to).

N2N is the number of Cards generated.

Elements may be merged to the nearest physical element with Card 6e NEARM option.

Elements connected with a conductance value > 1.0E10 are automatically merged.

The elements created by the Card 5d Space Element Card, and the reverse elements created with the Card 9 REVNODE are automatically merged.

The temperatures of the merged elements are recovered by the automatic creation of follower conductances. During the Analyzer run, the merged elements become SINK elements. This option may be disabled with the Card 9 PARAM NOMRECOV.

Hydraulic elements and Card 9 MCV elements may not be merged into other elements. However, other elements may be merged into them.

If elements with temperature-dependent specific heats or capacitances are merged, it is important to ensure that they all reference the same specific heat table.