Function for tracers #2361
Answered
by
glwagner
ammtD
asked this question in
Computational science!
Function for tracers
#2361
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Hi, I would like to force a tracer to a specific value at a specific time and location in my grid. Any creative suggestions on how to do this? Any help appreciated! |
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Answered by
glwagner
Mar 19, 2022
Replies: 2 comments 6 replies
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I think you'll have to chain @inline t_unforced(t) = t < ti
@inline i_unforced(i) = i < 1 | i > 3
@inline k_unforced(k) = k < 1 | k > 3
@inline unforced(i, k, t) = t_unforced(t) | i_unforced(i) | k_unforced(k)
@inline forcing(i, j, k, grid, clock, fields) = ifelse(unforced(i, k, clock.time), 0.0, 1.0)
c_forcing = Forcing(forcing, discrete_form=true)I think that will work... |
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3 replies
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Finally getting around to follow up on this component of my model construction... I've tried the above. In principle it seems to do the job, though once the forcing turns on the tracer field does look funny, a sequence of high and low values (see link to animation here).. Another problem I encounter is when I add a second condition on the first line (aiming to turn of the forcing at a certain time as well): Doesn't work, this model crashes with the error: |
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It's because of order-of-operations rules; @inline t_unforced(t) = (t < ti) | (t > tf)
@inline i_unforced(i) = (i < 1) | (i > 3)
@inline k_unforced(k) = (k < 1) | (k > 3)It's not too surprising that you see oscillatory errors / noise with a sharp forcing. You could consider smoothing the forcing out with ramps / |
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Oops sorry, OK. fixed that! Works nicely now, thank a lot! |
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Answer selected by
ammtD
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Has anyone tried this on a GPU? I use to apply a tracer forcing at a single surface grid cell over the first 15 days (using ClimaOcean's errors in |
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3 replies
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Ah, I think you need to declare the variables const i0 = 200
const j0 = 20
const k0 = Nz
const tf = 15daysAnother way to do this is to add the variables as @inline t_unforced(t, tf) = (t > tf)
@inline i_unforced(i, i0) = (i < i0) | (i > i0)
@inline j_unforced(j, j0) = (j < j0) | (j > j0)
@inline k_unforced(k, k0) = (k < k0) | (k > k0)
@inline unforced(i, j, k, t, p) = t_unforced(t, p.tf) | i_unforced(i, p.i0) | j_unforced(j, p.j0) | k_unforced(k, p.k0)
@inline forcing(i, j, k, grid, clock, fields, p) = ifelse(unforced(i, j, k, clock.time, p), zero(grid), one(grid))
c_forcing = Forcing(forcing, discrete_form=true, parameters=(; i0, j0, k0, tf))(I also removed the Also there are a few other ways to do this. For example you could use |
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Here's some relevant documentation for reference (and also if we see any chance to improve it!) https://clima.github.io/OceananigansDocumentation/stable/simulation_tips/ |
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Cool, thanks so much @glwagner! I have it working now. :) |
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I think you'll have to chain
|logic in adiscrete_formforcing function. I tried to make it readable:I think that will work...