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laomashu

2d_BC boundary in GPU

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Hi All,

 

I have done some test runs of rain on grid model by using GPU, the details are:

  • Boundary condition – 2d_bc HT type (statics tail water)
  • Run1 - 5m cell size
  • Run2 - 3m cell size
  • Run3 – 2m cell size
  • All runs are same except change cell size in TGC file

 

When checking the water level at the location near boundary, it was found that the results show the level is dropping after peak for 3m and 5m cell size model  runs. However the level for 2m cell size model is continually increasing, it seems the 2d_BC is not functioning. see attached file for more inforamtion.

 

Appreciated that someone can help.

 

Regards

 

Hai CGPU check.pdf

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Hai C

It may be that with the 2m model the time to peak is a little longer then the other sized models and you may need to run the 2 m grid model for a longer time period to see a similar result.

I would suggest running the 2m model for another hour to see if the peak is reached

I also note the the water levels are significantly different in your snap shots which may suggest other modelling instability within the model. I would welcome any comment from the from as to why there appear to be an increase in water levels?

 

Thanks David

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Hi Hai,

 

Are you able to check in the _bcc_check, the _grd_check and the _zpt_check.  I can think of a couple  of reasons that this could occur:

  • If the 2d HT boundary is not snapped to the active cells (2d_code) at 5m cells the boundary and active cells would select the same cells, and at fine cell sizes, there may be a gap between the active and the boundary cells.  This should be visible in the _bcc and _grd check files:
  • Check the elevations to make sure that no high elevations are occurring along the boundary.  If the boundary is snapped to the edge of the DEM and fine cell sizes, the zpt may fall just outside the DEM and therefore have no elevation assigned.

Let us know if it not one of the above and we can dig a bit deeper.

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Hi,

 

Thanks your reply, please see the attached screen plots of _bcc_check, grd_check and zpt_check for 2m and 5m cell size model. it is noticed that there are some high points at both end of 2d_bc line. I really like to figure out what is the model doing under 2m and 5m cell size.

 

Looking forward your reply soon.

 

Regards

 

Hai C

post-29518-0-04707400-1403247983_thumb.j

post-29518-0-80397200-1403247988_thumb.j

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Hi Hai,

 

Are you able to email through the log files (.tlf and .gpu.tlf) for the simulations through to support@tuflow.com and we'll take a look.

 

Phil

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