Question about the AHO

[EEMS_Team]

Thank you for your question. Have you read these previous threads and referred to the theory document?

How to manipulate horizontal diffusion coefficient?

Hello. I have a question about pollutant transport modeling of dye. I’d like to manipulate diffusion of pollutant cloud. In EFDC manual, AHO (horizontal eddy viscosity) is the same as mass diffusivity. (And, I understand that mass diffusivity is horizontal diffusion coefficient.) So, I changed AHO to check the variation of peak concentration of dye at a specific point. I think if AHO is the same as mass diffusivity, peak concentration should be decreased when AHO is increasing. …

Turbulent diffusion option

Hello, I have questions about the calcuation method of horizontal eddy viscosity in EFDC. As I know, there are three options to calculate horizontal eddy viscosity (=AH). From other postings, I understand that the first option “Disable HMD” uses a constant AH (AH = AHO) and the second option “Activate HMD with Smagorinsky” uses time varying AH (AH = AHO + result of smagorinsky model with AHD). But, I don’t undertstand the third option (Activate HMD with Smagorinsky, Wall Drag and …

Questions of terminology (AHO, AHD, AVO, and ABO)

Dear EFDC users, In efdc.inp fire, they are described as: * AHO: CONSTANT HORIZONTAL MOMENTUM AND MASS DIFFUSIVITY mm/s AHD: DIMESIONLESS HORIZONTAL MOMENTUM DIFFUSIVITY (ONLY FOR ISHDMF>0)* AVO: BACKGROUND, CONSTANT OR EDDY (KINEMATIC) VISCOSITY mm/s ABO: BACKGROUND, CONSTANT OR MOLECULAR DIFFUSIVITY mm/sIn EFDC interface, they are described as: AHO: Background/Constant Horizontal Eddy Viscosity mm/s AHD: Eddy Diffusivity (dimensionlees) * AVO: BACKGROU…

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