I am modeling a large tidal strait (Juan de Fuca) where the internal wave field is strong. I have been looking for a way to incorporate the impact of IW's in the eddy viscosity. Sukoriansky, et al. (NPG V13 pg 9) have recently proposed a scheme called Quasi-normal scale elimination (QNSE) which proports to include both turbulence and wave effects. In particular Kv does not go to very small values at high Ri. and their results with atmospheric models do seem to be an improvement over the standard K-epsilon closure. Has there been any activity to implement this or any other scheme for modeling Kv in stably stratified conditions?
Thanks
Wayne
eddy viscosity in stratified regions due to internal waves
there are a few suggested methods to modify a 2 equation model
1) Journal Ocean Dynamics
Issue Volume 57, Number 2 / April, 2007
Pages 151-156
On leakage of energy from turbulence to internal waves in the oceanic mixed layer , Kantha and Clayson
2) Journal of Physical Oceanography
Volume 34, Issue 2 (February 2004). pp505-512
Turbulence Closure, Steady State, and Collapse into Waves.
Helmut Baumert and Hartmut Peters
is this the kind of stuff you are looking for ???
1) Journal Ocean Dynamics
Issue Volume 57, Number 2 / April, 2007
Pages 151-156
On leakage of energy from turbulence to internal waves in the oceanic mixed layer , Kantha and Clayson
2) Journal of Physical Oceanography
Volume 34, Issue 2 (February 2004). pp505-512
Turbulence Closure, Steady State, and Collapse into Waves.
Helmut Baumert and Hartmut Peters
is this the kind of stuff you are looking for ???
Thank you for the references. However, they discuss the removal of tke due to the generation of new internal waves from turbulence (a process which has generated a major debate between those two groups).
I am more concerned with additions to the effective eddy viscosity by unresolved internal wave processes away from the bottom where the stratification is relatively strong. This has apparently always been a known omision with the standard closures. The Sukoriansky reference computes a viscosity at high Richardson numbers, >1, which is still about 25% of the value you would compute without any stratification. That is, they continue to predict turbulence well above Ri = .25 and find that there is really no sharp "critical Ri" where it suddenly drops. They have incorporated their scheme, which is mathematically quite complex, into a modified k-epsilon engine to get better results with some amospheric test cases. I was wondering if anyone has considered this for ROMS, or any other approach besides just increasing the background viscosity to accound for the waves.
Thanks again.
I am more concerned with additions to the effective eddy viscosity by unresolved internal wave processes away from the bottom where the stratification is relatively strong. This has apparently always been a known omision with the standard closures. The Sukoriansky reference computes a viscosity at high Richardson numbers, >1, which is still about 25% of the value you would compute without any stratification. That is, they continue to predict turbulence well above Ri = .25 and find that there is really no sharp "critical Ri" where it suddenly drops. They have incorporated their scheme, which is mathematically quite complex, into a modified k-epsilon engine to get better results with some amospheric test cases. I was wondering if anyone has considered this for ROMS, or any other approach besides just increasing the background viscosity to accound for the waves.
Thanks again.