3. Operands

3.1. Operand MODELE

♦ MODELE = mo

Name of the model whose mesh supports the acoustic calculation elements.

3.2. Operand DOUBLE_LAGRANGE

◊ DOUBLE_LAGRANGE = 'OUI'/'NON'

This keyword makes it possible to say whether or not the user wants to split the Lagrange multipliers used to define dualize the boundary conditions in the assembled matrix.

Concretely, splitting the Lagrange multipliers makes it possible to use linear solvers that do not allow pivoting. Not duplicating the Lagranges makes it possible to reduce the number of degrees of freedom of the problem (and therefore the size of the problem to be solved) but its use is limited to solvers MUMPS and Petsc.

3.3. Tags: PRES_IMPO

3.3.1. But

Key words: factors that determine the nature of the conditions imposed on the specified elements (knots or meshes).

♦ | PRES_IMPO

Allows you to impose the degree of freedom of pressure.

Allows you to specify the vibratory speed field imposed when loading on border elements.

3.3.2. Operands TOUT/GROUP_NO/GROUP_MA/SANS_GROUP_NO/SANS_GROUP_MA

Declaration of topological entities on which loads are applied, boundary conditions.

These are imposed on the knots or meshes given by the keywords TOUT, GROUP_MA, GROUP_NOtout by possibly excluding using the keywords SANS_ *.

Attention the keywords SANS_ * are only available for the keyword PRES_IMPO.

3.3.3. Operands PRES/IMPE

Value (complex) of the degree of freedom of sound pressure (the only degree of freedom in acoustic modeling) imposed on the specified nodes.

Value (complex) of the acoustic impedance imposed on the specified meshes.

3.4. Keyword LIAISON_UNIF

3.4.1. But

Keyword factor allowing the same value (unknown) to be imposed on the degrees of freedom of a set of nodes.

3.4.2. Operands GROUP_MA/GROUP_NO

These operands make it possible to define a list of \(n\) \({N}_{i}\) nodes whose redundancies have been eliminated (for GROUP_MA, it’s mesh connectivities).

3.4.3. Tag DDL

This operand can only be used in acoustic modeling, except the text “PRES”, defining the only degree of freedom allowed, the sound pressure \(p\).

The resulting conditions imposed are:

\(p({N}_{1})=p({N}_{i})\) for \(i\in \{\mathrm{2,}\mathrm{...},n\}\)