Divergence detected in AMG solver: k,epsilon,Increasing relaxation sweep?

BHOLU · May 9, 2018, 05:29

we're simulation mixing of jets problem in ANSYS (Fluent solver) for Mach 1.86 jets where jets are issuing from convergent-divergent nozzle into free atmosphere. The 2D domain is extended from C-D nozzle to free atmosphere.
The main highlights of simulation are

1. Density based solver (air is compressible): steady, axisymmetric
2. Ideal gas, Sutherland Viscosity
3. k-e realizable turbulence model
4. Solution method formulation : explicit
5. Default courant number = 5
6. Checked solution initialization for : Std., hybrid, fmg
But I'm getting Divergence in AMG solver with following error messege
# Divergence detected in AMG solver: Coupled -> Decreasing coarsening group size!
# Divergence detected in AMG solver: Coupled -> Increasing relaxation sweeps!
# You may try the enhanced divergence recovery with (rpsetvar 'amg/protective-enhanced? #t)
Divergence detected - temporarily reducing Courant number to 0.5
and trying again...
Divergence detected - temporarily reducing Courant number to 0.05
and trying again...
Divergence detected - temporarily reducing Courant number to 0.005
and trying again...
Divergence detected - temporarily reducing Courant number to 0.0005
and trying again...
Divergence detected - temporarily reducing Courant number to 5e-05
and trying again...
Internal error at line 1603 in file 'dbns\rp_mstage.c' on Node 0.

Please help some one help me.

aravinth · May 14, 2018, 02:41

change the convergence value for k and epsilon in residual and solve it !!

Heril1996 · September 25, 2020, 03:24

Quote:

Originally Posted by BHOLU

we're simulation mixing of jets problem in ANSYS (Fluent solver) for Mach 1.86 jets where jets are issuing from convergent-divergent nozzle into free atmosphere. The 2D domain is extended from C-D nozzle to free atmosphere.
The main highlights of simulation are

1. Density based solver (air is compressible): steady, axisymmetric
2. Ideal gas, Sutherland Viscosity
3. k-e realizable turbulence model
4. Solution method formulation : explicit
5. Default courant number = 5
6. Checked solution initialization for : Std., hybrid, fmg
But I'm getting Divergence in AMG solver with following error messege
# Divergence detected in AMG solver: Coupled -> Decreasing coarsening group size!
# Divergence detected in AMG solver: Coupled -> Increasing relaxation sweeps!
# You may try the enhanced divergence recovery with (rpsetvar 'amg/protective-enhanced? #t)
Divergence detected - temporarily reducing Courant number to 0.5
and trying again...
Divergence detected - temporarily reducing Courant number to 0.05
and trying again...
Divergence detected - temporarily reducing Courant number to 0.005
and trying again...
Divergence detected - temporarily reducing Courant number to 0.0005
and trying again...
Divergence detected - temporarily reducing Courant number to 5e-05
and trying again...
Internal error at line 1603 in file 'dbns\rp_mstage.c' on Node 0.

Please help some one help me.

i am facing same issue for same problem can you post the solution?

May 9, 2018, 05:29	Divergence detected in AMG solver: k,epsilon,Increasing relaxation sweep?	#1
BHOLU New Member BHOLU KUMAR Join Date: May 2018 Posts: 10 Rep Power: 8	we're simulation mixing of jets problem in ANSYS (Fluent solver) for Mach 1.86 jets where jets are issuing from convergent-divergent nozzle into free atmosphere. The 2D domain is extended from C-D nozzle to free atmosphere. The main highlights of simulation are 1. Density based solver (air is compressible): steady, axisymmetric 2. Ideal gas, Sutherland Viscosity 3. k-e realizable turbulence model 4. Solution method formulation : explicit 5. Default courant number = 5 6. Checked solution initialization for : Std., hybrid, fmg But I'm getting Divergence in AMG solver with following error messege # Divergence detected in AMG solver: Coupled -> Decreasing coarsening group size! # Divergence detected in AMG solver: Coupled -> Increasing relaxation sweeps! # You may try the enhanced divergence recovery with (rpsetvar 'amg/protective-enhanced? #t) Divergence detected - temporarily reducing Courant number to 0.5 and trying again... Divergence detected - temporarily reducing Courant number to 0.05 and trying again... Divergence detected - temporarily reducing Courant number to 0.005 and trying again... Divergence detected - temporarily reducing Courant number to 0.0005 and trying again... Divergence detected - temporarily reducing Courant number to 5e-05 and trying again... Internal error at line 1603 in file 'dbns\rp_mstage.c' on Node 0. Please help some one help me. Heril1996 likes this.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Error: Divergence detected in AMG solver	siri	FLUENT	8	March 12, 2018 18:08
Divergence detected in AMG solver: temperature	R4RAHUL	FLUENT	6	September 16, 2014 18:44
Divergence detected in AMG solver: pressure correction	xinquanzhoucn	FLUENT	5	July 21, 2014 05:49
Divergence detected in AMG solver: pressure coupled	n.jithin.1991	FLUENT	6	January 5, 2014 12:43
Quarter Burner mesh with periosic condition	SamCanuck	FLUENT	2	August 31, 2011 12:34

May 14, 2018, 02:41		#2
aravinth New Member Aravinth Join Date: May 2018 Location: Singapore Posts: 2 Rep Power: 0	change the convergence value for k and epsilon in residual and solve it !!