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(5.1 acoustics) Error Division by zero. - Function: /

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Hi guys,

I try to use pressure acoustics and thermoacoustics for no mean flow muffler simulation. No matter in 2D or 3D, comsol 5.1 always gives the error:

[in 3D case]
Division by zero.
- Function: /
Failed to evaluate expression.
- Expression: d(((-comp1.acpr.pwr1.keq*i*comp1.p*test(comp1.p)+(comp1.acpr.nx*mean(d(comp1.acpr.p_b,x))+comp1.acpr.ny*mean(d(comp1.acpr.p_b,y))+comp1.acpr.nz*mean(d(comp1.acpr.p_b,z)))*test(comp1.p)+0.5*(comp1.pTx*test(comp1.pTx)+comp1.pTy*test(comp1.pTy)+comp1.pTz*test(comp1.pTz))*i/comp1.acpr.pwr1.keq)*comp1.acpr.delta/comp1.acpr.rho_c)*(dvol),{test@18})

[in 2D case]
Division by zero.
- Function: /
Failed to evaluate expression.
- Expression:
d((2*(-comp1.acpr.pwr1.keq*i*comp1.p*test(comp1.p)+(comp1.acpr.nr*mean(d(comp1.acpr.p_b,r))+comp1.acpr.nz*mean(d(comp1.acpr.p_b,z)))*test(comp1.p)+0.5*(comp1.pTr*test(comp1.pTr)+comp1.pTz*test(comp1.pTz))*i/comp1.acpr.pwr1.keq)*comp1.acpr.delta*pi*r/comp1.acpr.rho_c)*(dvol),{test@15})
- Feature: Stationary Solver 1 (sol1/s1)

Could anyone give some hints on those error information?
Thank you!

1 Reply Last Post 2017年2月1日 GMT-5 11:07
COMSOL Moderator

Hello Fuxi Zhang

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Posted: 8 years ago 2017年2月1日 GMT-5 11:07
Hi Fuxi Zhang
it seems the same message error that you have when i try to modulate the 3 dimension using the semi-conductor module:
"" Division by zero.
- Function: /
Failed to evaluate variable.
- Variable: comp1.semi.adm2.Nd0
- Defined as: exp(-((comp1.semi.adm2.negr3/comp1.semi.adm2.chz)^2))*((((((comp1.semi.adm2.Nbox*comp1.semi.adm2.cp_dtd)*exp(-((comp1.semi.adm2.posr1/comp1.semi.adm2.chx)^2)))*exp(-((comp1.semi.adm2.negr1/comp1.semi.adm2.chx)^2)))*exp(-((comp1.semi.adm2.posr2/comp1.semi.adm2.chy)^2)))*exp(-((comp1.semi.adm2.negr2/comp1.semi.adm2.chy)^2)))*exp(-((comp1.semi.adm2.posr3/comp1.semi.adm2.chz)^2)))
Failed to evaluate variable.
- Variable: comp1.semi.adm2.Nd
- Defined as: comp1.semi.adm2.Nd0*comp1.semi.adm2.cp_dtd
Failed to evaluate variable.
.
.
.
.
.
so please any suggestion to solve it !!
thanks
Hi Fuxi Zhang it seems the same message error that you have when i try to modulate the 3 dimension using the semi-conductor module: "" Division by zero. - Function: / Failed to evaluate variable. - Variable: comp1.semi.adm2.Nd0 - Defined as: exp(-((comp1.semi.adm2.negr3/comp1.semi.adm2.chz)^2))*((((((comp1.semi.adm2.Nbox*comp1.semi.adm2.cp_dtd)*exp(-((comp1.semi.adm2.posr1/comp1.semi.adm2.chx)^2)))*exp(-((comp1.semi.adm2.negr1/comp1.semi.adm2.chx)^2)))*exp(-((comp1.semi.adm2.posr2/comp1.semi.adm2.chy)^2)))*exp(-((comp1.semi.adm2.negr2/comp1.semi.adm2.chy)^2)))*exp(-((comp1.semi.adm2.posr3/comp1.semi.adm2.chz)^2))) Failed to evaluate variable. - Variable: comp1.semi.adm2.Nd - Defined as: comp1.semi.adm2.Nd0*comp1.semi.adm2.cp_dtd Failed to evaluate variable. . . . . . so please any suggestion to solve it !! thanks

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