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 Unread post by fanqing »

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: 4091
Joined: Wed Jul 02, 2003 5:29 pm
Location: CFOS/UAF, USA

Re: LTRANS "jumped over a u element"

#2 Unread post by kate »

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

Re: LTRANS "jumped over a u element"

#3 Unread post by ian »

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

Re: LTRANS "jumped over a u element"

#4 Unread post by fanqing »

Yes, changing the time step seems to have solved the problem. Thanks!
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fanqing
Posts: 14
Joined: Thu Jan 20, 2005 6:16 pm
Location: North Carolina State University

Re: LTRANS "jumped over a u element"

#5 Unread post by fanqing »

Is there a recommended idt value, maybe depending on the spatial resolution?
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ian
Posts: 6
Joined: Mon Apr 15, 2013 7:05 pm
Location: umces

Re: LTRANS "jumped over a u element"

#6 Unread post by ian »

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

Re: LTRANS "jumped over a u element"

#7 Unread post by fanqing »

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

Thanks,
Fanqi
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kate
Posts: 4091
Joined: Wed Jul 02, 2003 5:29 pm
Location: CFOS/UAF, USA

Re: LTRANS "jumped over a u element"

#8 Unread post by kate »

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

Re: LTRANS "jumped over a u element"

#9 Unread post by fanqing »

I just found it was used for this purpose:
http://omgrhe.meas.ncsu.edu/RHE/Northet ... npress.pdf
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ian
Posts: 6
Joined: Mon Apr 15, 2013 7:05 pm
Location: umces

Re: LTRANS "jumped over a u element"

#10 Unread post by ian »

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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