LTRANS "jumped over a u element"

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fanqing
Posts: 14
Joined: Thu Jan 20, 2005 6:16 pm
Location: North Carolina State University

LTRANS "jumped over a u element"

#1 Post by fanqing » Wed Feb 18, 2015 5:30 pm

Hi,

I was running LTRANS and came across the problem of "jumped over a u element" or "jumped over a v element" problem (error info listed below)

" Previous Location:
x: -7221945.47253313 y: 2073598.67415 247
lon: -64.8772335292822 lat: 18.3081033479963

Current Location:
x: -7221948.21037701 y: 2073618.07464950
lon: -64.8772581242805 lat: 18.3082688073524

The Program Cannot Continue and Will Terminate

Any suggestions how to overcome this problem?
Thanks.

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kate
Posts: 3718
Joined: Wed Jul 02, 2003 5:29 pm
Location: IMS/UAF, USA

Re: LTRANS "jumped over a u element"

#2 Post by kate » Wed Feb 18, 2015 5:44 pm

I haven't run LTRANS, but perhaps it's complaining that the time-step is too long? It probably has the same sort of CFL condition as the ROMS model.

ian
Posts: 6
Joined: Mon Apr 15, 2013 7:05 pm
Location: umces

Re: LTRANS "jumped over a u element"

#3 Post by ian » Thu Feb 19, 2015 5:37 am

fanqing wrote:Hi,

I was running LTRANS and came across the problem of "jumped over a u element" or "jumped over a v element" problem (error info listed below)

" Previous Location:
x: -7221945.47253313 y: 2073598.67415 247
lon: -64.8772335292822 lat: 18.3081033479963

Current Location:
x: -7221948.21037701 y: 2073618.07464950
lon: -64.8772581242805 lat: 18.3082688073524

The Program Cannot Continue and Will Terminate

Any suggestions how to overcome this problem?
Thanks.
Decrease the internal timestep in LTRANS.data. The variable name is idt.

fanqing
Posts: 14
Joined: Thu Jan 20, 2005 6:16 pm
Location: North Carolina State University

Re: LTRANS "jumped over a u element"

#4 Post by fanqing » Thu Feb 19, 2015 6:33 pm

Yes, changing the time step seems to have solved the problem. Thanks!

fanqing
Posts: 14
Joined: Thu Jan 20, 2005 6:16 pm
Location: North Carolina State University

Re: LTRANS "jumped over a u element"

#5 Post by fanqing » Thu Feb 19, 2015 6:34 pm

Is there a recommended idt value, maybe depending on the spatial resolution?

ian
Posts: 6
Joined: Mon Apr 15, 2013 7:05 pm
Location: umces

Re: LTRANS "jumped over a u element"

#6 Post by ian » Fri Feb 20, 2015 5:39 am

fanqing wrote:Is there a recommended idt value, maybe depending on the spatial resolution?
Yes, the value is highly dependent on the spatial resolution and the particle velocities.

The model will not allow a particle to move through a gridcell without being effected by its properties, so smaller gridcells and larger velocities require smaller idt values.

fanqing
Posts: 14
Joined: Thu Jan 20, 2005 6:16 pm
Location: North Carolina State University

Re: LTRANS "jumped over a u element"

#7 Post by fanqing » Thu Mar 05, 2015 5:12 pm

Can LTRANS be used to simulate oil spill trajectory and fate?

Thanks,
Fanqi

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kate
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Joined: Wed Jul 02, 2003 5:29 pm
Location: IMS/UAF, USA

Re: LTRANS "jumped over a u element"

#8 Post by kate » Thu Mar 05, 2015 6:28 pm

LTRANS was designed for tracking biological critters within the ocean. You could probably use it to track surface objects, but I doubt it has the oil weathering processes or the effect of winds on oil.

One could of course add them since the source is out there.

fanqing
Posts: 14
Joined: Thu Jan 20, 2005 6:16 pm
Location: North Carolina State University

Re: LTRANS "jumped over a u element"

#9 Post by fanqing » Thu Mar 05, 2015 6:46 pm

I just found it was used for this purpose:
http://omgrhe.meas.ncsu.edu/RHE/Northet ... npress.pdf

ian
Posts: 6
Joined: Mon Apr 15, 2013 7:05 pm
Location: umces

Re: LTRANS "jumped over a u element"

#10 Post by ian » Fri Mar 06, 2015 6:35 am

fanqing wrote:Can LTRANS be used to simulate oil spill trajectory and fate?

Thanks,
Fanqi
Yes, actually it can!

We have not released this code to the public yet, but I believe some others have independently done so. Keep on the look out for LTRANS 3.0!

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