Several doubts about physical processes and technical information

Question

Hi there,

There is some information that I have not found in the manual (I am looking at the old ELCOM science manual, the new AEM3D user manual and the Hodges et al, 2000). I will really appreciate any information:

1) How does the model compute the air density? Is it constant or there are formulations?
2) I read the mixing model and the RANS equations descriptions and I did not find when to use the drag coefficient CD. Is it used by AEM3D just if the Underflow module is activated?
3) I found that DIFFUSIVITY is for horizontal diffusivities of transportable scalars, but I could not find anything about  horizontal eddy viscosity in the user manual. How can I set-up this value in the model? Does the model solve this horizontal turbulent diffusion along to the vertical mixing model? I can not identify this.
4) I understand that vertical mixing model using TKE budget is the recommended model in stratified systems, but I am wondering if the current AEM3D is supporting other vertical turbulence models.
5) Is there more information about the dynamic bottom module? Maybe in the AEM3D Science manual, but it is  not with the model folder when it is downloaded.
6) When do you recommend to activate the Underflow model?, I did some tests in a reservoir using the old ELCOM model but I did not see important changes, so maybe it works with some special conditions, any suggestion how should I use this option?
7) finally, could you provide the science manual for AEM3D?

Thank you in advance

Best

Ricardo RB

Answer 1

1) air density is by default set to 1.25 but this constant can be modified in the run_aem3d.dat file using the coefficient rho_air

2) drag coefficient is used in the free surface solution

3) Diffusion of momentum can be added using the keys default_diffusivity_velocity of default_diffusivity_velocity_x.  But bear in mind the Euler Lagrange Momentum solution is numerically quite diffuse.

4) We don't have other mixing models implemented

5) We don't have any documentation on this yet, but it's fairly simple with just settling and resuspension of particles leading to change in bottom height.

Comments

Thank you for your information chris. Best

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Hi
We bought the AEM3D license last month and just started to work with the model. Would be very usefull for us to have the scientific manual that you  mention.
Can you send me a copy?
thanks in advance
Guillermo (from Uruguay)

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Hi.
Follow the below link to get information of old ELCOM-Manuals. Perhaps it can help you to understand some insights. However, things have changed with AEM3D.

https://drive.google.com/drive/folders/1YNKa5IhMHmtJ7uadQ3S4cYjVEqYH8hUA?usp=sharing

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Thanks a lot  Ricardo!!
It will help us a lot.
regards
GG