Hi, when I run the EFDC, it stopped and occurred problem as :“maximum iterations exceeded in external solution”, someone told it maybe the Bathymetry too complicated and EE couldn’t deal with it. If it ture, How can I fix it OR maybe other reasons caused it? Please help me, thanks~

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*** This EFDC_DSI_OMP Run used: 4 thread(s) ***

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SCANNING INPUT FILE: EFDC.INP

SCANNING INPUT FILE: ASER.INP

SCANNING INPUT FILE: QSER.INP

SCANNING INPUT FILE: WSER.INP

ALLOCATING ARRAYS

ZEROING REAL ARRAYS

ZEROING Integer ARRAYS

READING THE MAIN EFDC CONTROL FILE: EFDC.INP

DEBUG ON

READING CELL.INP

READING CELLLT.INP

READING DXDY.INP

READING QSER.INP

READING WSER.INP

NUMBER OF WIND SERIES= 1

ANEMOMETER HEIGHT (m)= 10.0

NSNAPSHOTS= 7670

READING LXLY.INP

MAXIMUM ITERATIONS EXCEEDED IN EXTERNAL SOLUTION

TAP ANY KEY TO EXIT EFDC_DSI

Jenny, Welcome to the forum. The most likely cause of your model crash is because it is not converging. You you might want to look into your time step. Try to decrease your time step and see if you get working model. What are the range of your DX and DY ? What is the time step you used ? I hope these posts would help you solve your problem. Thanks. Best, Janesh Devkota

Hi,I have changed time step and Dx/Dy. But the question “Maximum Iterations exceeded in external solutions” still exist.

And I cannot fix it. Can you help me? Thanks~

DX:800

DY:800

CELL:186

step:80s

AUTOSTEPPING SUMMARY (WITH SAFETY FACTOR):

METHOD1: MOMENTUM CHECK (DT,L): 0.0000 0

METHOD2: ADVECTION CHECK (DT,L): 0.0000 0

METHOD3: BTM FRICT CHECK (DT,L): 0.0000 0

METHOD4: LIM DHDT,I,J,DTM (DT,L):

-------------------------------------------------------------------------------

TIME TIME ELEV VELE VELN DYE AV AB VELE VELN DYE AV

IN STEP SURF SURF SURF SUR SURF SURF BOTT BOTT BOTT BOTT

DAYS SEC CM CM/S CM/S PPM CM/S CM/S CM/S CM/S PPM CM/S LMIN

-------------------------------------------------------------------------------

4383.001 80.000 15796 -3 -1 0 0 0 -3 -1 0 0 0

MAXIMUM ITERATIONS EXCEEDED IN EXTERNAL SOLUTION

TAP ANY KEY TO EXIT EFDC_DSI……

Did you try to run your model with time steps 50s, 30s and 20s to see if any one those time step worked in the successful model simulation ?

Janesh

Jenny wrote:Hi,I have changed time step and Dx/Dy. But the question "Maximum Iterations exceeded in external solutions" still exist.

And I cannot fix it. Can you help me? Thanks~

DX:800

DY:800

CELL:186

step:80s

AUTOSTEPPING SUMMARY (WITH SAFETY FACTOR):

METHOD1: MOMENTUM CHECK (DT,L): 0.0000 0

METHOD2: ADVECTION CHECK (DT,L): 0.0000 0

METHOD3: BTM FRICT CHECK (DT,L): 0.0000 0

METHOD4: LIM DHDT,I,J,DTM (DT,L):

-------------------------------------------------------------------------------

TIME TIME ELEV VELE VELN DYE AV AB VELE VELN DYE AV

IN STEP SURF SURF SURF SUR SURF SURF BOTT BOTT BOTT BOTT

DAYS SEC CM CM/S CM/S PPM CM/S CM/S CM/S CM/S PPM CM/S LMIN

-------------------------------------------------------------------------------

4383.001 80.000 15796 -3 -1 0 0 0 -3 -1 0 0 0

MAXIMUM ITERATIONS EXCEEDED IN EXTERNAL SOLUTION

TAP ANY KEY TO EXIT EFDC_DSI……

It seemed like you are using the Dynamic time step by entering the Safety Factor. Please try to set as "0" for the Safety Factor and also test your model with 50s, 30s, and so on...

Hoping this helps.

Dear forum, I’m working a prepare graduates and it nedd to use EFDC. In this period, I have had a problem as figure above. Can anybody say to me where was it mistake? And How to fix its? Thank for any help!

Hello Phanmanhwru,

The most likely cause of your error is the time step you used in your model simulation.

However, you also need to check your boundary conditions i.e., make sure you have all the numeric in your data. Sometimes, there might be non-numeric characters in the time series as well. So, I would suggest lowering and time step. If lowering time step doesn’t help then there should be something wrong in your boundary condition.

It seems you have dynamic time step. Try to set up your model without dynamic time step and see whether it helps. If you really want to specify the dynamic time step, try to play a bit with the safety factor.

Btw, please consider writing a new question rather than asking on a question that has already been answered.

Best,

Janesh Devkota

Thank Sir,

My model wasn’t run because flag, and then I have fixed it, so it run.

Thank for your help!

Under the Simulation Timing Option of the EFDC+ Model, the following options exist: Time Steps (Seconds), Safety Factor, Maximum dH/dT, and Growth Step; Please, how do these options affect model run and output?

Under the Simulation Timing Option of the EFDC+ Model, the following options exist: Time Steps (Seconds), Safety Factor, Maximum dH/dT, and Growth Step; Please, how do these options affect model run and output?