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azahrafa

RMA2 or ADCIRC?

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Hello, I'm a student and currently learning to use SMS. I'm using it to simulate sedimentation in an estuary. There are some questions I'd like to ask.

What's the difference between RMA2 and ADCIRC? And if the study location is in an estuary in a small strait where the waves are not very strong, and the depth of the location I’m observing range from 0-50 meters would it be appropriate to use RMA2? Or would ADCIRC be more appropriate?

Thank you,

Azahrafa

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Both RMA2 and ADCIRC are finite element schemes but have their own strengths and weaknesses. RMA2 has better boundary conditions for river inflows but if you keep your boundary conditions far from the area of interest it isn't that big of a deal.

RMA2 can have long timesteps but each takes longer to compute than an ADCIRC timestep so the overall runtime is probably generally comparable.

ADCIRC works really well in coastal situations and many models run clear out to very deep water where boundary conditions are simple. However, you can also use it in smaller areas. ADCIRC is easier to add wind forcing.

Both models can be a little troublesome if there is a lot of wetting and drying. If this is the case in your situation, you may consider SRH which uses the generic model interface and is more stable in this situation.

I'm not sure how you are going to do sedimentation but if you are planning to use PTM it is a little easier to setup in ADCIRC because PTM reads its file formats natively while you have to convert your output to use RMA2.

You really should be able to use either model in this situation.

Hello, I'm a student and currently learning to use SMS. I'm using it to simulate sedimentation in an estuary. There are some questions I'd like to ask.

What's the difference between RMA2 and ADCIRC? And if the study location is in an estuary in a small strait where the waves are not very strong, and the depth of the location I’m observing range from 0-50 meters would it be appropriate to use RMA2? Or would ADCIRC be more appropriate?

Thank you,

Azahrafa

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Thanks for replying. :) Oh, so both models are appropriate for my location, but RMA2's better to use when you have river inflow boundary conditions, while ADCIRC on the other hand is better when wind force is important. Did I get that right? I've tried using RMA2, and to simulate the sediment transport I imported the output from RMA2 to SED2D, but I couldn't get it to run, error keeps occurring, I'm still trying to work on that. I haven't tried using ADCIRC though. and I've never heard of PTM before. What is it?

Thanks a lot. :)

Azahrafa

Both RMA2 and ADCIRC are finite element schemes but have their own strengths and weaknesses. RMA2 has better boundary conditions for river inflows but if you keep your boundary conditions far from the area of interest it isn't that big of a deal.

RMA2 can have long timesteps but each takes longer to compute than an ADCIRC timestep so the overall runtime is probably generally comparable.

ADCIRC works really well in coastal situations and many models run clear out to very deep water where boundary conditions are simple. However, you can also use it in smaller areas. ADCIRC is easier to add wind forcing.

Both models can be a little troublesome if there is a lot of wetting and drying. If this is the case in your situation, you may consider SRH which uses the generic model interface and is more stable in this situation.

I'm not sure how you are going to do sedimentation but if you are planning to use PTM it is a little easier to setup in ADCIRC because PTM reads its file formats natively while you have to convert your output to use RMA2.

You really should be able to use either model in this situation.

Edited by azahrafa

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Your summary of the models is correct. I guess my answer is somewhat simplistic as a thorough comparison would take more time and probably help from others more familiar with each.

There are two kinds of models that you can use for sediment transport type analysis. Eulerian models do analysis on a mesh or grid and have answers that can be contoured at each node or cell. These types of models often use an approach analyzing velocities and shear stresses to determine if sediment is being eroded or deposited. Lagrangian models on the other hand represent a mass of material as a representative particle. In PTM, this mass is referred to as a parcel. The number of parcels largely determines the runtime so there is a reasonable limit on how many parcels you can have. Each parcel is pushed around by currents (and sometimes waves). It movement and settling is affected by its size and density. Individual particles may settle out and later get resuspended. SMS has some tools for determining the thickness of sediment deposited and some other basic analysis tools.

As mentioned, PTM is a Lagrangian model and can be run as a post-process of any of the numeric models in SMS but is tied more directly to ADCIRC than most. SMS doesn't have a lot of options for Eulerian models. We removed Sed2D from our interface because it seemed to be difficult to use and there were issues with both the model and the interface. It became unprofitable for us to invest in maintaining it. The best Eulerian model within SMS for your situation may be CMS-Flow. However, the way you describe the model PTM may be a good approach. You would provide information on incoming sediment and see if it settles out or gets carried through to the downstream end of the model.

I hope this helps.

Thanks for replying. :) Oh, so both models are appropriate for my location, but RMA2's better to use when you have river inflow boundary conditions, while ADCIRC on the other hand is better when wind force is important. Did I get that right? I've tried using RMA2, and to simulate the sediment transport I imported the output from RMA2 to SED2D, but I couldn't get it to run, error keeps occurring, I'm still trying to work on that. I haven't tried using ADCIRC though. and I've never heard of PTM before. What is it?

Thanks a lot. :)

Azahrafa

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