Hi,
I’m just trying out EFDC Explorer 7.2 with a 144 x 56 x 10 grid…the program says it’s exceeded the maximum number of iterations (it says this after it writes out the first line of the tabulated output). Is this normal for this size grid? What do you suggest be done to fix this?
Thanks!
David
Hi David,
What is the time step you used in the model ? Usually this type of error occurs when your time step is larger. Have you tried reducing your time step and rerun the model ? The time step needs to satisfy the CFL condition.
Best,
Janesh Devkota
Janesh,
Thanks for you response. I “fixed” the iteration problem by increasing the maximum number of iterations from 200 to 5000. The time step is 86.4 seconds. Now I have a new problem, the model gives me negative depths!
The problem I am running is very simple: A rectangular lake that is 1440 m long 590 m wide and 20 m deep, circulation driven by a surface wind of 5 m/s. The starting depth of the water column is 20 m. What could be causing negative depths…before the program gives any actual calculated depths?
David
Hi,
I am facing the same issue as David with the negative depths. I have a very simple 1D model of a river with varying cell widths and lengths. There are a total of 106 cells representing the river. I have setup the bathymetry and boundary conditions from results of a different hydrologic model. I have 17 cells with Flow BCs, which are high resolution flow time series. I have 17 cells with hydraulic structure boundary conditions which are defined by Depth/Flow rating tables.
I have enabled the wet/dry option with “-99” and have tried using dynamic time step with safety factor of 0.7 and 1000 iterations (ramp-up loops). I still have the issue with negative depths.
Please help!
Sannan
Hello David and Sannan,
The negative depth in the model is caused by the bad initial / boundary conditions in the model. Please check your initial and boundary conditions again before running the model.
If you can post your model here, then I might be able to look at it and figure out what was wrong.
Thanks.
Best,
Janesh
Hi Janesh,
When I changed the number of iterations to 2000, the model ran. The open south BC was initially a time series, however this should be a constant value. When I set the open south boundary condition to a constant water elevation for the entire time period of the model, the model ran for 57.958 days after which it crashed reporting a “Single Val Control Structure Table Out of Bounds” error. I understand that this error may be because of the out of bound value in one of the rating tables. I am posting the link to my model here:
https://www.dropbox.com/sh/zrfdxtuleyfswzz/AAC7bhE-3T0RdQKSxpNWiyiSa?dl=0
I also have other issues, and I am not sure if this is the right post for it. When I look at the results from 57 days, I get bi-directional flows at my river station at i,j = 5,60, which should not be the case. I think this may be because of the hydraulic structures? Should I use channel modifiers instead? The river I am modeling contains custom cross-sections such as culverts and bridges.
Thank you very much for all your help.
Sannan
Janesh,
The link to my model is at:
Dropbox - Error
Still obtaining negative depths at an interior node. Any guidance would be appreciated.
David
Hi Janesh,
Please disregard my previous model that I sent. I realized that I had a completely invalid grid. Sorry for the post.
Sannan
Sannan, No problem.
David, I looked at the input files you posted on the dropbox. I looked at your domain and it seems that your domain size is pretty small. The cell size you have is 10m by 10 m. So, the time step you had was pretty large. I changed the time step to 10 seconds and ran the model for few days and it is now running properly. So, make sure to check your time step.
Thanks.
Best,
Janesh Devkota