Re: [Anuga-user] regarding_stage_in_river_channel

[Rajesh T. <tai...@gm...>]

Hi Rudy,

Thanks for immediate reply...

I want to model section of river with Base flow before some higher flow...
As of now I dont have my script with me...
Does it require good programming skills to create sections of polygon on
the fly ( at runtime)... because I want that only...

regards,
Rajesh Tailor


On Mon, Dec 17, 2012 at 4:59 PM, Rudy <ru...@ba...> wrote:

>  Hi Rajesh,
>
> It would help me immensely, to help you if you could fully describe
> Exactly what it is you are trying to achieve, and why?
>
> If you describe what you need to do, I may be able to provide the steps to
> achieve it?
>
> - Is it a dam break for a reservoir?
> - Are you modelling a section of river with Base flow before some higher
> flow?
> - Please describe what it is you are trying to model ???
>
> Other wise send a copy of your run script.... and I will try to interpret
> what your script is doing .....
>
> ( You need to create Polygons external to ANUGA, and then reference the
> filenames in your script)
>
> Regards Rudy
>
>
>
> On 17/12/2012 10:08 PM, Rajesh Tailor wrote:
>
> Thanx Ole and Rudy,
>
>  I haven't used Dam break scenario, so can you please tell me how to
> break polygon into section on the fly (do you have any inbuilt API in anuga
> or seperate python script for doing that), I have tried on google but
> couldn't found anything...
>
>  I can't use the above method (suggested by Rudy) because I cant run the
> model twice so I have to take constant stage as an initial condition... and
> I have tried this but instead of extracting stage quantity only, I tried to
> take existing  sww as a domain but It was not working... dont know why....
> It was printing step interval from evolve method but It was not appending
> new changes to sww file ....
>
>  But I think whatever Ole has suggested, I can go with that... constant
> stage for multiple polygon sections...
>
>  any help about this will be appreciated...
>
>  regards,
> Rajesh Tailor
>
>
> On Sun, Dec 16, 2012 at 3:29 AM, Rudy <ru...@ba...> wrote:
>
>>  Its sounds like a little confusion is creeping into the discussion:
>>
>> I will try to clear it up...
>>
>> 1. Is a constant stage (Flat horizontal water surface) required, or a
>> constant Depth ?
>> 2. If it is indeed Stage then the method I outlined previously using a
>> Polygon over the extent of the river set to a Fixed Stage works !
>>
>> 3. If a constant depth is required, .... really it is a nonsense as the
>> depth will follow the terrain ???
>> 4. If a constant Maximum Depth is Required based on the lowest elevation
>> along the river (there is no effective function to achieve this)
>>     ( Could play around with Numpy.where   I suppose...) But I dont think
>> this is the outcome you want...
>>
>> As Ole has stated, it is usually easiest to pre wet the river by either:
>> - Providing Boundary Conditions
>> - Or placing a flow in the river and letting it come to steady state
>> before running rainfall....
>>   ( You could run with flow to steady, extract the stage from SWW, then
>> load that Stage as initial condition before running rainfall ) ....
>>
>> It would be best that Rajesh, clearly defines exactly what it is that is
>> needed.... so as to provide best advice back to him....
>>
>> Regards Rudy
>>
>>
>>
>>
>>
>> On 15/12/2012 5:41 PM, Ole Nielsen wrote:
>>
>> Hi Rajesh
>>
>>   You asked me about giving stage to river polygon and gave me two
>>> choices...
>>> either provide constant depth which we can provide using add_quantity()
>>> or provide constant stage...
>>>
>>
>>>  I want to give constant stage over the river polygon, for that you
>>> have suggested to break polygon into sections and set stage for each..
>>>
>>>  How can I break the river polygon in sections at runtime..
>>>
>>
>>  I thought, you could create polygons before the run - i.e. have the
>> river consisting of a series of predefined polygons and then set the
>> constant level in each. I thought you wanted to do this as an initial
>> conditions. Isn't that right.
>>
>>  However, thinking more about it I am not sure this will be such a good
>> idea because the minute you start running, water will start moving due to
>> steps in the river water surface. Perhaps it'd be better run the model for
>> a while only with boundary conditions to reach a steady state, then start
>> your rainfall or what have you. Would that make sense? Rudy, can you
>> comment?
>>
>>  And for boundary condition I want the situation in which water run into
>>> the model and at the boundary it should flow out of the domain...
>>>
>>
>>  If you don't care so much about velocities at each end, then use a
>> straight Dirichlet boundary conditions with your desired stage (and zero
>> for the momentum).
>> If you have a timeseries for water levels you want to impose at the
>> inlet, you can use the boundary called something like Set stage
>> transmissive momentum.
>>
>>  Does this make sense?
>>
>>  Cheers
>> Ole
>>
>>
>>>
>>>  regards,
>>> Rajesh Tailor
>>>
>>
>>
>>
>
>