cohesive sediment with BOTTOM_CONC and CONTINUOUS keywords

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cyrilgarneau@gmail.com
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Joined: Tue Oct 18, 2011 12:28

cohesive sediment with BOTTOM_CONC and CONTINUOUS keywords

Postby cyrilgarneau@gmail.com » Wed Jul 10, 2013 14:57

Dear all,

Working with the Mohid River Network, I have an unexpected behaviour when using the cohesive sediments with the CONTINUOUS keyword: Apparently, the bottom concentration of cohesive sediment at the end of my warmup period is not recorded in the *.fin file. This results in an initial bottom concentration estimated (I don't know how) based on the cohesive sediment in suspension, thus not reading the BOTTOM_CONC keyword (that holds the initial concentration of the bottom).

Since I need an erodable bed stream, I need a significant bed concentration. The BOTTOM_MIN_CONC use leads to numerical instability (that I did not investigate), so I have to use a different solution to provide erodable material. My question is: Do I do something worng? If not, is it possible to record the bottom concentration in the *.fin file?

At the moment, I work around the issue by setting an unrealistic concentration of sediment in the water (with very high erosion). At the beginning of the continuous simulation, I only need a few simulated days of warmup with correct erosion parameters to get normal quantities in the water.

Thank you

davidbrito
MOHID Advanced user
Posts: 190
Joined: Thu Jan 01, 1970 00:00

Re: cohesive sediment with BOTTOM_CONC and CONTINUOUS keywor

Postby davidbrito » Tue Jul 16, 2013 17:39

Hello Cyrill,

When a simulation ends the .fin file is writen and with it it goes the bottom concentration of each property if BOTTOM_FLUXES for that property are activated.
When a continuous simulation is done the model will look for the bottom concentration of the final file of the previous simulation if BOTTOM_FLUXES for that property are activated.

In a continuous simulation the BOTTOM_CONC is ignored, as it should, since you are continuing a previous simulation.
BOTTOM_CONC is a user definition for the initial condition, only used when no continuation is performed. BOTTOM_CONC is not the keeper of any computed concentration is a initial condition for bottom. In continuous computation you do not need initial conditions defined by the user as the computed are saved in the end of the previous run.


So the initial bottom concentration in a continuous simulation is not by nay means estimated and it should be the same as the last one of the previous run. You should plot the bottom concentration in these two simlations and verify these. If not tell us.


BOTTOM_MIN_CONC only limits the amount of bottom mass that can remain in the bottom. If the erosion takes material and in the bottom is left less than this BOTTOM_MIN_CONC than the erosion is fixed to leave, as minimum, that mass.


So I hope I may have clarified and I would suggest you to upload here a graph with the bottom concentration of the previous simulation and this one so we can see if something is wrong.

Best regards,
David

cyrilgarneau@gmail.com
MOHID Beginner
Posts: 19
Joined: Tue Oct 18, 2011 12:28

Re: cohesive sediment with BOTTOM_CONC and CONTINUOUS keywor

Postby cyrilgarneau@gmail.com » Thu Nov 14, 2013 18:48

Hi David,

I think I found the problem relating to my (old) bottom flux problem: In ModuleDrainageNetwork.F90, function "ReadInitialFile()", I can read the concentrations of all properties without problem. However, the code then loops over the properties to fill the BottomFlux vector of each property in the following code (lines 4713 to 4717 in my version):

Code: Select all

 
       do while (associated(Property))
            read (InitialFile, err=10) Property%BottomConc
            Property => Property%Next
        end do


The problem is that an error is returned and the BottomFlux vector is not filled.

That leads me to believe that either the bottom flux is not recorded at the end of the warm up simulation or I forgot a keyword to record it. Of course, the BOTTOM_FLUX keyword is activated in all of my simulations for particulate properties, both during the warmup simulation and in the continuous one.

Do you see where my problem might be?

cyrilgarneau@gmail.com
MOHID Beginner
Posts: 19
Joined: Tue Oct 18, 2011 12:28

Re: cohesive sediment with BOTTOM_CONC and CONTINUOUS keywor

Postby cyrilgarneau@gmail.com » Thu Nov 14, 2013 19:05

Hi David,

I still have to do some tests, but I still found a potential bug that you might be interested in: My problem was that the properties were not stated in the same order in my warmup simulation than in my continuous simulation. From what I understand of the *.fin file, it is filled sequentially, which means that declaring first "dissolved metal" then "particulate metal" in my warmup file and doing the opposite in my continuous simulation leads mohid to initialize my "particulate metal" with the data from my "dissolved metal" property.

As I understood that keywords and properties could be stated anywhere in the simulation text files, I never had the chance to get proper results. In any case, I believe that the case is solved for me.

Thank you again for your help.

Jauch
Site Admin
Posts: 98
Joined: Thu Jan 01, 1970 00:00

Re: cohesive sediment with BOTTOM_CONC and CONTINUOUS keywor

Postby Jauch » Thu Nov 14, 2013 19:58

Hello Cyril,

cyrilgarneau@gmail.com wrote:My problem was that the properties were not stated in the same order in my warmup simulation than in my continuous simulation. From what I understand of the *.fin file, it is filled sequentially, which means that declaring first "dissolved metal" then "particulate metal" in my warmup file and doing the opposite in my continuous simulation leads mohid to initialize my "particulate metal" with the data from my "dissolved metal" property.


In fact, you're right. All the modules in Mohid, not only DrainageNetwork, that deals with properties, write and read the fin file sequentially, using the order in which the properties appear.

cyrilgarneau@gmail.com wrote:As I understood that keywords and properties could be stated anywhere in the simulation text files, I never had the chance to get proper results.


You are right, again. The properties/keywords can be on any location in the input data file. But the order must be the same in continuous simulations.

This is not exactly a "bug", but for sure is not the safest methodology.
I'll let this issue to the developers group and try to see if we can do something about it.

Thanks.
Eduardo Jauch.

davidbrito
MOHID Advanced user
Posts: 190
Joined: Thu Jan 01, 1970 00:00

Re: cohesive sediment with BOTTOM_CONC and CONTINUOUS keywor

Postby davidbrito » Fri Nov 15, 2013 19:59

This problem comes from the fact that some info in .fin files are recorded in binary. In the case of not talking of properties the order they are written is the order they are read so there is no problem. But in the case of properties, and Drainage Network is the only case in MOHID Land where properties are written in binary for final file, if the user switches the order of properties between simulations it can read properties wrongly from other properties.


We will fix this by printing everyting in final file in HDF format and not binary. And in this case because it will read the property names it will not have a problem.


Very well Cyril! this is a very tricky problem found in MOHID Land!
Thanks a lot for the insight!

Best regards,
David


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