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Global Equations

Posted 20 sept. 2014, 23:14 UTC−4 Version 4.4 0 Replies

Chin Neng Leong
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Hi,

I'm having a problem in defining an ODE by using Global Equations. In the model, I add stress at solid.S11, solid.S12...etc so that the model undergoes deformation. At the same time, I apply pressure at the inner surface whose value is determined from an ODE (P+R*C*Pt+(R+R_c)*Vt+R*R_c*C*Vtt=0). R, C and R_c are constants while P is the pressure, Pt is its 1st time derivative. V is the volume of the inner hemisphere and Vt, Vtt are its 1st and 2nd time derivative respectively.

However, I'm having computational error with message:
"Failed to find consistent initial values.
Attempt to evaluate real square root of negative number.
Function: sqrt
Failed to evaluate variable.
Variable: comp1.solid.J, Defined as: sqrt((((((comp1.solid.Cl13*((2*comp1.solid.Cl12)..."

Can any1 help me with this? Thank you.

CN

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0 Replies Last Post 20 sept. 2014, 23:14 UTC−4
COMSOL Moderator

Hello Chin Neng Leong

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