Viscous force and memory allocation #113

marinlauber · 2024-03-14T14:44:53Z

This implements a simple viscous force routine. Following the structure of the routine for the pressure force, which needs to include the time of the simulation to make sure we are measuring at the correct time, see #110;

Also, it is allocating like crazy, same as for the pressure force routine.

This is a work in progress.

marinlauber · 2024-06-11T08:54:25Z

This fixes #110 by providing a higher-level interface function for the force routines. It also adds a moment computation routine. I will add some proper tests soon.

marinlauber · 2024-06-13T12:46:03Z

This is ready for review @weymouth @b-fg. I have added some examples I had lying around that show some of the capabilities added recently, but they didn't have an example.

I also removed the type argument in loc and related functions.

b-fg · 2024-06-13T14:03:54Z

src/util.jl

@@ -121,8 +121,8 @@ using StaticArrays
 Location in space of the cell at CartesianIndex `I` at face `i`.
 Using `i=0` returns the cell center s.t. `loc = I`.
 """
-@inline loc(i,I::CartesianIndex{N},T=Float64) where N = SVector{N,T}(I.I .- 1.5 .- 0.5 .* δ(i,I).I)
-@inline loc(Ii::CartesianIndex,T=Float64) = loc(last(Ii),Base.front(Ii),T)
+@inline loc(i,I::CartesianIndex{N}) where N = SVector{N}(I.I .- 3//2 .- 1//2 .* δ(i,I).I)


Have you checked this works on GPU? It was not working for me on the AD branch.

No, I have not

Ok, it probably won't. We are currently using 1.5f0... because otherwise it doesn't work in GPUs.

I will revert to the type conversion of the SVector for now. We can sort this out later.

src/util.jl

src/Metrics.jl

b-fg · 2024-06-17T15:11:54Z

There are currently no tests for ∮τnds nor ∇²u.

marinlauber · 2024-06-17T15:19:49Z

I can add a test for that!

Co-authored-by: Bernat Font <[email protected]>

…ations. Note that the reduction (sum) is always performed over Float64 type. Updated tests and examples with the new functions.

b-fg · 2024-06-21T14:20:12Z

All tests passing locally on CPU and GPU.

@marinlauber the modifications I did to your previous changes (up to bb99599) make all the metrics work for GPU now, since that implementation was only working for CPU. The allocations are very good as well (there are just a few more, but the routines are also a bit faster):

# Tests using SIMD execution (single-thread mode) and Array backend:

# Previous (bb99599)
# Pressure force: 0.040567 seconds (4 CPU allocations: 176 bytes)
# Viscous force: 0.343564 seconds (4 CPU allocations: 176 bytes)

# Current changes (d01f68c)
# Pressure force: 0.035714 seconds (39 CPU allocations: 1.562 KiB)
# Viscous force: 0.310422 seconds (38 CPU allocations: 1.516 KiB)

The only remaining thing to discuss is the examples added. Only the TwoD_cylinderVIV.jl had to be changed to comply with this PR, and the other examples do not actually even use any force/moment metric. I suggest we remove those changes from this PR and create a new one just for examples. Then this PR should be ready to merge.

b-fg · 2024-06-21T14:22:40Z

@weymouth can you please give it a look before we merge to master?

…examples. These examples do not use force metrics so they should be submitted in a different PR.

marinlauber · 2024-06-21T14:29:53Z

Are we ok with discontinuing the ∮nds function?

weymouth

Looks good, except for that one default, which I can fix.

weymouth · 2024-06-21T14:29:23Z

src/AutoBody.jl

@@ -112,6 +112,11 @@ function measure(a::Bodies,x,t)
    sdf, map, _ = sdf_map_d(a.bodies,a.ops,x,t)
    measure(sdf,map,x,t)
 end
+# measures the distance, normal, and velocity accuratly for sdf≤1
+function measure_fast(body::AutoBody,x,t)
+    abs(body.sdf(x,t))>1 && return zero(eltype(x)),zero(x),zero(x)


Why doesn't this return d, zero(x), zero(x)?

It's an error, should return d.

b-fg · 2024-06-21T14:35:44Z

Are we ok with discontinuing the ∮nds function?

Yeap, we will just keep the high-level functions since it was difficult to do multiple dispatch of ∮nds applied to 2D/3D scalar/vector fields.

b-fg · 2024-06-21T14:36:35Z

Looks good, except for that one default, which I can fix.

Which one?

b-fg · 2024-06-21T15:25:03Z

The promote_type works but makes it a tiny bit slower even if there are less allocations:

# Tests using SIMD execution (single-thread mode) and Array backend:

# Previous changes (d01f68c)
# Pressure force: 0.035714 seconds (39 CPU allocations: 1.562 KiB)
# Viscous force: 0.310422 seconds (38 CPU allocations: 1.516 KiB)

# Current changes (0f70067)
# Pressure force: 0.142078 seconds (19 CPU allocations: 800 bytes)
# Viscous force: 0.402344 seconds (19 CPU allocations: 768 bytes)

The price to pay for having these functions AD-compatible is fine though (plus with KA in CPU or GPU the difference is very small!) :)

Make Simulation mutable and loc(T=Float32)

marinlauber added 2 commits March 14, 2024 15:40

add viscous force method

f273bc3

add moment routine and simplify force function input

b2cd89b

fix large allocation in force computations

2d25295

marinlauber marked this pull request as ready for review June 11, 2024 14:37

marinlauber and others added 5 commits June 13, 2024 14:06

polish force and moment functions and update examples

bb345bb

add some examples that I had

9c0710b

Merge branch 'weymouth:master' into viscous_force

4d153e8

remove unused types

236c9c4

merge master for final pull request commit

9c6a593

b-fg reviewed Jun 13, 2024

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b-fg reviewed Jun 14, 2024

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b-fg reviewed Jun 14, 2024

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b-fg reviewed Jun 14, 2024

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marinlauber and others added 5 commits June 18, 2024 08:48

Update src/Metrics.jl

97c93e0

Co-authored-by: Bernat Font <[email protected]>

fix type error and ad tests for viscous force and moment

bb99599

Forces and moments now working on both GPU and CPU with minimal alloc…

4caf9d6

…ations. Note that the reduction (sum) is always performed over Float64 type. Updated tests and examples with the new functions.

Fixed unnecessary type anotation in nds function definition.

92017dc

Merged master.

d01f68c

b-fg requested a review from weymouth June 21, 2024 14:22

Removed TwoD_MultipleBodies.jl, TwoD_Square.jl, and TwoD_Triangle.jl …

a9acc43

…examples. These examples do not use force metrics so they should be submitted in a different PR.

weymouth reviewed Jun 21, 2024

View reviewed changes

faster and type general

0f70067

b-fg merged commit 36dc237 into WaterLily-jl:master Jun 21, 2024
21 checks passed

marinlauber mentioned this pull request Jun 26, 2024

add some examples and update README.md #136

Closed

weymouth referenced this pull request Jul 22, 2024

Merge pull request #149 from WaterLily-jl/mutable-sim

d23ac35

Make Simulation mutable and loc(T=Float32)

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Viscous force and memory allocation #113

Viscous force and memory allocation #113

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Viscous force and memory allocation #113

Viscous force and memory allocation #113

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