[mary779]

hi guys.can somebody tell me that what this error means? i am really confused. after 617 iteration this error happened.
i am modeling a two phase flow problem in a pipe ( a horizontal pipe with gravity at x-direction=+9.81 , so it behaves like a vertical pipe with downward flow) . (diameter=2.5 cm - length=1 m) for symmetric model i used this size of mesh=125 * 10000
saturated water (laminar) at inlet with 0.011 kg/s mass flow rate and wall's temperature=378.15 kelvin
and i am using transient - vof - courant number=0.23 - solution method = simple and for momentum and energy = quick , for volume fraction = Geo-Reconstruct - under relaxation factors: momentum=0.2 , pressure=0.5 - time step=0.001
do you have any suggestion that how can i fix this error ? i really appreciate your help.
excuse me if i didn't explain my problem good. i am new to CFD.
thanks, mary

[hwet]

decrease time step to get rid of this, it could or could not help with the convergence

[mahipal parmar]

hi..i am trying to solve double pipe heat exchanger using inserts in CFD.
i used- double precision,
energy eq-on
model-turbulent(2 eq,stnd wall fun)

solution method:-SIMPLe(PRESSURE-VELOCITY BASED)-second order
my energy residules are not converges during solution.so ans is not converged.

boundary conditions:-
hot inlet:-mass flow rate-1.3 kg/s,inlet temp-413 k
hot outlet-pressure based
cold inlet:-mass flowrate-1.3, temp-298 k
cold outlet:-pressure base

any one have solution?plz guide me.
thanks in advance.

[bhargavbharathan]

Originally Posted by mahipal parmar

hi..i am trying to solve double pipe heat exchanger using inserts in CFD.
i used- double precision,
energy eq-on
model-turbulent(2 eq,stnd wall fun)

solution method:-SIMPLe(PRESSURE-VELOCITY BASED)-second order
my energy residules are not converges during solution.so ans is not converged.

boundary conditions:-
hot inlet:-mass flow rate-1.3 kg/s,inlet temp-413 k
hot outlet-pressure based
cold inlet:-mass flowrate-1.3, temp-298 k
cold outlet:-pressure base

any one have solution?plz guide me.
thanks in advance.

Hi,

Have you tried reducing the URF?

-BB

[mahipal parmar]

thanks for reply bhargav..
yes i reduced the URF and i got the convergence of energy residual.
thanks again.