Hydrodynamic_ Approx

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ceciletheodore@acceptablesavenirs.eu
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Posts: 9
Joined: Thu Jan 01, 1970 00:00

Hydrodynamic_ Approx

Postby ceciletheodore@acceptablesavenirs.eu » Thu Nov 03, 2011 09:58

Hi,

I tried to run my simulation with Dynamic Wave and after, with Kinematic Wave equation, in drainage network module.

It worked perfectly with the Dynamic Wave, but I got an error message with the Kinematic Wave :

" -------------------- DRAINAGE NETWORK --------------------

Number of Nodes : 2194
Number of Reaches : 2193
Number of Outlets : 1
Hydrodynamic Approx. : Kinematic wave
Numerical Scheme : ExplicitScheme
Downstream Boundary : Zero depth gradient

-------------------------- MOHID -------------------------

Running MOHID Land, please wait...

Number of iterations above maximum
Check DT configurations
ModifyDrainageNetLocal - ModuleDrainageNetwork - ERR03"

Then I tried to change the DT parameter (from 60 to 500) in Model module, but it didn't work.

"START : 1999 12 1 0 0 0
END : 2000 1 31 0 0 0
DT : 60
VARIABLEDT : 1
MAXDT : 3600
GMTREFERENCE : 0
DT_PREDICTION_INTERVAL : 60"

May I ask why it doesn't work with the kinematic wave equation and what parameter I need to change?

Regards,

Cécile

frank.maretec@ist.utl.pt
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Re: Hydrodynamic_ Approx

Postby frank.maretec@ist.utl.pt » Tue Nov 08, 2011 22:23

Dear Cécile,

I changed a lot of code related with this recently. The dynamic wave options (most complete equation) is the one I use most and works best...

What you have to do is not to change the DT parameter, but the MAXDT parameter. Try using a lower value. Also start initially with a lower DT (e.g 1).

Also assure that you don't start with rough numerical conditions (high discharges right in the beginning, etc).

Hope this helps,
Frank
In order to understand recursivity you must first understand recursivity.

frank.maretec@ist.utl.pt
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Re: Hydrodynamic_ Approx

Postby frank.maretec@ist.utl.pt » Wed Nov 09, 2011 11:00

Dear Cécile,

just one more input. If your problem presists, you can reduce the "TIME_STEP_SPLIT" in module Drainage network.

This is something new I implemented and speeds up significantly model performance, but has the risk that you run into the problem you faced.

So, if the problem presists, try to put the following line in your Drainage_Network_x.dat file:

TIME_STEP_SPLIT : 1

(you can try different options, the default value is 10)

Hope this helps,
Frank
In order to understand recursivity you must first understand recursivity.

ceciletheodore@acceptablesavenirs.eu
MOHID Beginner
Posts: 9
Joined: Thu Jan 01, 1970 00:00

Re: Hydrodynamic_ Approx

Postby ceciletheodore@acceptablesavenirs.eu » Thu Nov 24, 2011 09:44

Hi,

Thanks Frank for this advice.
It works better with the TIME_STEP_SPLIT parameter.

Cécile


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