Convergence in multiphase flow(transient) simulation

mari009 · July 19, 2018, 12:04

Hi all..,
I am running a two phase fluid flow problem(water and air). Initially atm air filled inside the container then Liquid enters container passes through various compartment and leaves the container. I need to solve the case as transient problem ,mesh size – 0.55 million .It takes a lot of time to solve(min 02 days).kindly anybody assist me to solve the case at faster rate.
Model : Vof, Implicit , Realizable, K-Ԑ
Volume of container : 0.000121 m3
Area of inlet : 0.000622 m2
Area of Outlet : 0.00049 m2

Studentt · July 30, 2018, 11:21

reduce the detail of the mesh (unless you need the very high detail) and lower the relaxation factors (in setup>solution>controls)

Rajaero · July 31, 2018, 00:04

Hi,
1.what about your mesh quality?
2. which residual is not converging ? (ex, continuity,momentum,energy,vof)
3. if your mesh Skewness is over 0.9 its very hard converge
4. generally, multi phase problem convergence rate is very slow
5. please post your residual image

Thanks...

subhankarnits · September 25, 2018, 17:36

Hi sir.
I have same problem can you help me?
If you give me your mail I'll send you details of my problem.

mohammadrezazakeri · October 6, 2018, 18:00

hello im doing cfd smulation solar still in fluent later press calculate
im recieve error
Solar Loading model output:
Internally Scattered Energy [W]: 281.802, Ambient Flux [W/m^2]: 65.9987
Boundary ID: 5, Integral Energy Source [W]: 1.656799e+02
Boundary ID: 8, Integral Energy Source [W]: 1.#QNAN0e+00
Boundary ID: 9, Integral Energy Source [W]: 1.#QNAN0e+00
Boundary ID: 12, Integral Energy Source [W]: 1.#QNAN0e+00
Total Integral Energy Source [W]: 1.#QNAN0e+00
Compute Time: 0 sec
radiation resid. = 1.#QOe+00
radiation resid. = 1.#QOe+00
radiation resid. = 1.#QOe+00
radiation resid. = 1.#QOe+00
radiation resid. = 1.#QOe+00
maximum iterations exceeded in radiation calculations.

please help me

July 19, 2018, 12:04	Convergence in multiphase flow(transient) simulation	#1
mari009 New Member Muthu Join Date: Feb 2012 Location: chennai Posts: 4 Rep Power: 14	Hi all.., I am running a two phase fluid flow problem(water and air). Initially atm air filled inside the container then Liquid enters container passes through various compartment and leaves the container. I need to solve the case as transient problem ,mesh size – 0.55 million .It takes a lot of time to solve(min 02 days).kindly anybody assist me to solve the case at faster rate. Model : Vof, Implicit , Realizable, K-Ԑ Volume of container : 0.000121 m3 Area of inlet : 0.000622 m2 Area of Outlet : 0.00049 m2

July 31, 2018, 00:04	suggestions	#3
Rajaero Member Taiwan,new north city Join Date: Aug 2017 Location: Taiwan Posts: 74 Rep Power: 8	Hi, 1.what about your mesh quality? 2. which residual is not converging ? (ex, continuity,momentum,energy,vof) 3. if your mesh Skewness is over 0.9 its very hard converge 4. generally, multi phase problem convergence rate is very slow 5. please post your residual image Thanks...

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July 30, 2018, 11:21		#2
Studentt New Member London Join Date: Jul 2018 Posts: 2 Rep Power: 0	reduce the detail of the mesh (unless you need the very high detail) and lower the relaxation factors (in setup>solution>controls)

September 25, 2018, 17:36		#4
subhankarnits Member subhankar das Join Date: Jul 2018 Posts: 32 Rep Power: 7	Hi sir. I have same problem can you help me? If you give me your mail I'll send you details of my problem.

October 6, 2018, 18:00		#5
mohammadrezazakeri New Member mohammadreza Join Date: Oct 2018 Posts: 2 Rep Power: 0	hello im doing cfd smulation solar still in fluent later press calculate im recieve error Solar Loading model output: Internally Scattered Energy [W]: 281.802, Ambient Flux [W/m^2]: 65.9987 Boundary ID: 5, Integral Energy Source [W]: 1.656799e+02 Boundary ID: 8, Integral Energy Source [W]: 1.#QNAN0e+00 Boundary ID: 9, Integral Energy Source [W]: 1.#QNAN0e+00 Boundary ID: 12, Integral Energy Source [W]: 1.#QNAN0e+00 Total Integral Energy Source [W]: 1.#QNAN0e+00 Compute Time: 0 sec radiation resid. = 1.#QOe+00 radiation resid. = 1.#QOe+00 radiation resid. = 1.#QOe+00 radiation resid. = 1.#QOe+00 radiation resid. = 1.#QOe+00 maximum iterations exceeded in radiation calculations. please help me