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/ALE/SOLVER/FINT

Block Format Keyword This option defines the numerical method for internal force integration. This is relevant only for brick element and ALE legacy solver (momentum equation solved with FEM).

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/ALE/SOLVER/FINT
Iform                

Definitions

Field Contents SI Unit Example
Iform Integration method (internal force for brick elements) flag.
= 0
Set to 3.
= 1
Volume integration of the stress tensor using a shape function.
= 2
Surface integration for the hydrostatic stress tensor only.
= 3 (Default)
Surface integration for the stress tensor.

(Real)

 

Comments

  1. Momentum equation has local form:
    (1)
    ρut+div(ρuu)=div(σ)+ρg
    Iform is a flag defining the numerical method to compute div(σ) when integrated over the cell with legacy solver (nodal velocities).
    Iform=1
    Fint=Ωdiv(σ)dV
    Was the default method up to Radioss version 2019.
    Iform=2
    Fint=-ΩpdS+Ωdiv(σ)dV
    The integration method used with obsolete card /CAA (Obsolete)
    Iform=3
    Fint=Ω(-pI+σdev)dS
    The integration method used as of Radioss version 2020.
    For volume integration, shape functions are used to compute at node, N:(2)
    FiNint=σikΦNxk|0|Ω|

    Where, i=1,3

    The value ΦNxk|0 is taken at the integration point. It is assumed that:(3)
    ΦN1xj=ΦN7xj ; ΦN2xj=ΦN8xj ; ΦN3xj=ΦN5xj ; ΦN4xj=ΦN6xj

    This assumption is exact for parallelepipedic shape only, which is why the new default value method is set to surface integration (Iform=3).