Error:/(divide):invalid argument

aja1345 · December 24, 2015, 04:59

Hi,

I am simulating a turbine. Turbine have a small gap on the tip(Tip clearance). Number of nod in tip clearance is equal to 10. Turbulence model is k-e-non equlibrium.

When number of cell is about 500000 in the whole computational domain, convergence is very good(without adapt) and when i adapt on the blade and Tip clearance(only on the Tip of blade), solution diverges and the following error appears. Why???

Number of cell after adapting is equal to 1600000. In fact, adapt in region of Tip clearance is massive(only on the Tip of blade).

What does this happen??

A brief description of my work:

Due to the circumferential symmetry, only one eight of the annulus has been computed, imposing periodic boundary conditions in the tangential direction. The computational domain has been restricted in the axial direction to four chord lengths upstream and eight chord lengths downstream of the blade.

Thanks.

Best.

Aja

aja1345 · December 24, 2015, 05:20

Also, Now i understood that if i don't adapt the region of Tip Clearance and just i adapt on the blade, solution again diverges!!!

Why???????

aja1345 · December 24, 2015, 05:23

Flow is formed until iteration of 1612 and convergence is good but suddenly message of reversed flow and turbulent viscosity limited to viscosity ratio appear. Why????

I am grateful that guide me about this problem.

aja1345 · December 24, 2015, 05:35

In post2 , I typed wrong that i correct it.

"
Also, Now i understood that if i don't adapt the region of Tip Clearance and just i adapt on the blade, solution again diverges!!!

Why???????"

December 24, 2015, 04:59	Problem of Convergence---Error:/(divide):invalid argument	#1
aja1345 Senior Member Aja Join Date: Nov 2013 Posts: 496 Rep Power: 15	Hi, I am simulating a turbine. Turbine have a small gap on the tip(Tip clearance). Number of nod in tip clearance is equal to 10. Turbulence model is k-e-non equlibrium. When number of cell is about 500000 in the whole computational domain, convergence is very good(without adapt) and when i adapt on the blade and Tip clearance(only on the Tip of blade), solution diverges and the following error appears. Why??? Number of cell after adapting is equal to 1600000. In fact, adapt in region of Tip clearance is massive(only on the Tip of blade). What does this happen?? A brief description of my work: Due to the circumferential symmetry, only one eight of the annulus has been computed, imposing periodic boundary conditions in the tangential direction. The computational domain has been restricted in the axial direction to four chord lengths upstream and eight chord lengths downstream of the blade. Thanks. Best. Aja Last edited by aja1345; December 25, 2015 at 07:08.

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December 24, 2015, 05:20		#2
aja1345 Senior Member Aja Join Date: Nov 2013 Posts: 496 Rep Power: 15	Also, Now i understood that if i don't adapt the region of Tip Clearance and just i adapt on the blade, solution again diverges!!! Why???????

December 24, 2015, 05:23		#3
aja1345 Senior Member Aja Join Date: Nov 2013 Posts: 496 Rep Power: 15	Flow is formed until iteration of 1612 and convergence is good but suddenly message of reversed flow and turbulent viscosity limited to viscosity ratio appear. Why???? I am grateful that guide me about this problem.

December 24, 2015, 05:35		#4
aja1345 Senior Member Aja Join Date: Nov 2013 Posts: 496 Rep Power: 15	In post2 , I typed wrong that i correct it. " Also, Now i understood that if i don't adapt the region of Tip Clearance and just i adapt on the blade, solution again diverges!!! Why???????"