Choosing model for plume into stratified pond.

Roark · December 13, 2012, 15:48

I am trying to decide on a model to use. The goal of the project is to model the change in stratification in a pond when warm water is injected as a jet. It is important that buoyancy effects and the jet are accurately modeled but I want to know long term (order days, not weeks) influences on pond stratification.

I initially though about using Fluent, but the period of interest is of order days while inflow duration is of order hours. I think the timesteps constraints will make using Fluent not unfeasible.

I am only interested in vertical dynamics so a 2D-model is fine. CE-QUAL-W2 is a laterally averaged 2D model for environmental purposes and is designed for longer time scales. I may be able to crank up the resolution and try to model the inflow, but I am not sure if this is appropriate.

Does anybody have any advice on what model to select for this project? Words of wisdom will be greatly appreciated!

FMDenaro · December 13, 2012, 16:33

Quote:

Originally Posted by Roark

I am trying to decide on a model to use. The goal of the project is to model the change in stratification in a pond when warm water is injected as a jet. It is important that buoyancy effects and the jet are accurately modeled but I want to know long term (order days, not weeks) influences on pond stratification.

I initially though about using Fluent, but the period of interest is of order days while inflow duration is of order hours. I think the timesteps constraints will make using Fluent not unfeasible.

I am only interested in vertical dynamics so a 2D-model is fine. CE-QUAL-W2 is a laterally averaged 2D model for environmental purposes and is designed for longer time scales. I may be able to crank up the resolution and try to model the inflow, but I am not sure if this is appropriate.

Does anybody have any advice on what model to select for this project? Words of wisdom will be greatly appreciated!

I am not sure to understand your flow problem... I assume the flow is turbulent, isn't it? So, are you sure the 2D RANS makes sense?

However, I worked on buoyancy-induced flow but using LES, may you can find some help in the references cited in:

- Ocean Modelling, Vol. 17, pp. 199-218 (2007)
- http://link.springer.com/article/10....162-010-0202-x

Roark · December 13, 2012, 17:13

Thanks Filippo,

That is cool work, but I don't think I need that much detail! I need to investigate how the lake stratifies, generally. LES is way too computationally expensive for this purpose. RANS should do just fine. I am not sure though if the 2D approach is appropriate.

Roark · December 13, 2012, 17:25

Maybe there is an ocean-type model which will work. Any ideas?

FMDenaro · December 13, 2012, 17:36

Quote:

Originally Posted by Roark

Maybe there is an ocean-type model which will work. Any ideas?

yes, there are some models that focuses on the vertical prevalence of the flow, you should try to get the lectures at CISM in 2004

FMDenaro · December 13, 2012, 17:38

also, one of my collegues worked on flow in lakes, see the references
http://www.szn.it/SZNWeb/cmd/ShowArc...=HUMANRESOURCE

Roark · December 13, 2012, 19:17

I guess I can't rule Flow-3D out either. But I am still concerned that Flow-3D and Fluent are not appropriate for a multi-day simulation.

December 13, 2012, 15:48	Choosing model for plume into stratified pond.	#1
Roark New Member Simon Join Date: Dec 2012 Location: Colorado Posts: 16 Rep Power: 13	I am trying to decide on a model to use. The goal of the project is to model the change in stratification in a pond when warm water is injected as a jet. It is important that buoyancy effects and the jet are accurately modeled but I want to know long term (order days, not weeks) influences on pond stratification. I initially though about using Fluent, but the period of interest is of order days while inflow duration is of order hours. I think the timesteps constraints will make using Fluent not unfeasible. I am only interested in vertical dynamics so a 2D-model is fine. CE-QUAL-W2 is a laterally averaged 2D model for environmental purposes and is designed for longer time scales. I may be able to crank up the resolution and try to model the inflow, but I am not sure if this is appropriate. Does anybody have any advice on what model to select for this project? Words of wisdom will be greatly appreciated!

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December 13, 2012, 17:13		#3
Roark New Member Simon Join Date: Dec 2012 Location: Colorado Posts: 16 Rep Power: 13	Thanks Filippo, That is cool work, but I don't think I need that much detail! I need to investigate how the lake stratifies, generally. LES is way too computationally expensive for this purpose. RANS should do just fine. I am not sure though if the 2D approach is appropriate.

December 13, 2012, 17:25		#4
Roark New Member Simon Join Date: Dec 2012 Location: Colorado Posts: 16 Rep Power: 13	Maybe there is an ocean-type model which will work. Any ideas?

December 13, 2012, 17:38		#6
FMDenaro Senior Member Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,768 Rep Power: 71	also, one of my collegues worked on flow in lakes, see the references http://www.szn.it/SZNWeb/cmd/ShowArc...=HUMANRESOURCE

December 13, 2012, 19:17		#7
Roark New Member Simon Join Date: Dec 2012 Location: Colorado Posts: 16 Rep Power: 13	I guess I can't rule Flow-3D out either. But I am still concerned that Flow-3D and Fluent are not appropriate for a multi-day simulation.