[ThatHimalayanGuy]

Hi all,

Apologies in advance for the long post ahead. As a beginner to REEF3D, I want to understand what kind of simulations we can potentially run with REEF3D. I have following queries:


1. Boundary conditions of fixed discharge, inlet and outlet levels.
I tried the tutorial 9_5 Flow around a Circular Pier with different boundary conditions. In the ctrl file, I put followings conditions:
F 40 3
F 50 3 \\fixed level set for inflow and outflow
F 60 0.3 \\initial water level in domain
F 61 0.3 \\fixed inlet water level
F 62 0.15 \\fixed outlet water level
W 10 0.1 \\ 0.1m3/s discharge

After I ran the simulation, the water level in outlet and inlet, inflow rate were maintained. However the outflow rate was not the same as inflow rate. The development of the flow rates can be seen here: InflowOutflow_development.PNG
How can I achieve the balance in inflow and outflow? Or was I too impatient to reach a steady state condition?


2. Recontinue an existing simulation
Suppose a simulation was run for 60 seconds of simulated time but after post processing, I realize that I should have continued the simulation for longer time. How do we continue the simulation from the end time of initial simulation instead of starting over from 0 seconds?


3. Recontinue a simulation with finer mesh
Can we pre-run a simulation with coarser grid resolution to achieve steady state and then recontinue the same simulation with finer resolution?


4. Multiple Solid STLs
I realize that importing stl is only possible by naming the file 'solid.stl'. Is it possible to import multiple STL files for complex geometries which cannot be defined by 'S' functions in DIVEMesh?


5. Roughness for Topography + Solid stl
I was able to import topography from geodat and structures from solid.stl separately. Is it possible to define different roughness values for topography and solid? B 50 is for global wall roughness and B 51-56 have options for different walls, but these would not work on this scenario. This would be important for simulations such as optimization of hydropower structures.


6. Porous object definition
Can we separately define topography, solid stl and porous media within a single domain? B 240 option has function to define porous media as rectangular box, but would it work simultaneously with topography and solids defined within the domain? Also, how can we define porous media for more complex regions (which are non-rectangular or cannot be defined by B 270, 274 281).



7. Scouring simulation with natural bathymetry
I stumbled upon couple of demonstrations of scour simulation around pier and pipe structures in the forum. But they were all performed using the function S 57 (Sediment end, z-direction for whole domain ). Is it possible to rather define an existing sediment bed using the topography (geodat or stl) instead of S 57? It would be very interesting to perform scour simulations under complex arrangements and river bathymetry.



Once again, apologies for the long post

Looking forward to answers and performing more simulations with REEF3D.
Thank you very much!


- Rabs

[kamath]

Hi,
I can possibly answer parts of your question

1. Possibly not yet at steady state. Check the console output, however. Specifically Volume 1 and Volume 2 at the start (step 1) and at the time step that you stopped the simulation. Are they the same? Or was there a conservation problem (water volume reduces)

2. You can do this through the hot start option. This requires you to save a state file using P 40 and P 41/42 options. Then to continue, I 30 1. I 241 x. This functionality is currently broken though. There is an upgrade coming I hear.

3. Same answer as above as for 2. But current not working due to the overhaul in progress.

4. Merge all your stls into one file. I dont think multiple stls are supported.

5. Have not worked with this.

6. Yes, the three can work in a single domain. For complex objects, you need to build it from the available primitives: box and wedge

7. Have not worked with this.

Hope this helps

[Ronja]

Regarding 7.
I answered a similar question in this thread:
Generating sediment bed and scouring simulation


Hope that helps

[Curiousli]

Originally Posted by kamath

Hi,
I can possibly answer parts of your question

1. Possibly not yet at steady state. Check the console output, however. Specifically Volume 1 and Volume 2 at the start (step 1) and at the time step that you stopped the simulation. Are they the same? Or was there a conservation problem (water volume reduces)

2. You can do this through the hot start option. This requires you to save a state file using P 40 and P 41/42 options. Then to continue, I 30 1. I 241 x. This functionality is currently broken though. There is an upgrade coming I hear.

3. Same answer as above as for 2. But current not working due to the overhaul in progress.

4. Merge all your stls into one file. I dont think multiple stls are supported.

5. Have not worked with this.

6. Yes, the three can work in a single domain. For complex objects, you need to build it from the available primitives: box and wedge

7. Have not worked with this.

Hope this helps

Hello.
Regarding question 1, I have a doubt, what does volume 1 and volume 2 represent in fluid simulation? Phase 1 - volume of water and Phase 2 - volume of air? Are they still the same during the scouring simulation? If they are the same, can the sediment volume be seen?

[kamath]

Yes, correct. However I don't remember the order. You will figure it out from the relative values and the actual amount of air and water in your domain.
They should remain a constant for mass conservation.
Sediment data in Sediment log. I don't think there is volume, but I dont wor with sediments