Logging pressure solver

[marinlauber]

This is a draft pull request that implements some changes in the pressure solver.

A sample of the pressure solver log can be found here.
WaterLily.log

Changes:

• add @debug via LoggingExtras.jl to monitor the pressure residuals, iterations, etc.
• remove the adaptive multilevel pressure solver and increase the size of the smallest domain to N>=8
• add a test of the impulsive flow around a cylinder to check the pressure forces and oscillations in the pressure field.

Things to do:

• custom logging to free the @debug macro and use @logmsg instead for the pressure logging, see https://github.com/JuliaLogging/LoggingExtras.jl
• [ ] Type dispatch of the adaptive/non-adaptive multilevel pressure solver depending on the precision?
• [ ] some proper pressure solve tests

[weymouth]

Where is the logger used in this example?

[marinlauber]

Just by calling WaterLily.logger(...) triggers the @debug macros to print the expression behind to the log file. If this is not done @debug is not evaluated. Line 37 of test_psolver.jl

[weymouth]

Can you include an example of reading the file? And add a sample plot as a comment to this PR?

[marinlauber]

I am not sure what to do with the plotting script for the logger, it's really ugly and I don't want to include in into util.jl. I put it here for now...

using Plots

function plot_logger(fname="WaterLily.log")
    predictor = []; corrector = []
    open(fname,"r") do f
        readline(f) # read first line and dump it
        which = "p"
        while ! eof(f)  
            s = split(readline(f) , ",")          
            which = s[1] != "" ? s[1] : which
            push!(which == "p" ? predictor : corrector,parse.(Float64,s[2:end]))
        end
    end
    predictor = reduce(hcat,predictor)
    corrector = reduce(hcat,corrector)

    # get index of all time steps
    idx = findall(==(0.0),@views(predictor[1,:]))
    # plot inital L∞ and L₂ norms of residuals for the predictor step
    p1=plot(1:length(idx),predictor[2,idx],color=:1,ls=:dash,label="predictor initial r∞",yaxis=:log,size=(800,400),dpi=600,
            xlabel="Time step",ylabel="L∞-norm",title="Residuals",ylims=(1e-6,1e0),xlims=(0,length(idx)))
    p2=plot(1:length(idx),predictor[2,idx],color=:1,ls=:dash,label="predictor initial r₂",yaxis=:log,size=(800,400),dpi=600,
            xlabel="Time step",ylabel="L₂-norm",title="Residuals",ylims=(1e-6,1e0),xlims=(0,length(idx)))
    # plot final L∞ and L₂norms of residuals for the predictor
    plot!(p1,1:length(idx),vcat(predictor[2,idx[2:end].-1],predictor[2,end]),color=:1,lw=2,label="predictor r∞")
    plot!(p2,1:length(idx),vcat(predictor[3,idx[2:end].-1],predictor[3,end]),color=:1,lw=2,label="predictor r₂")
    # plot the MG iterations for the predictor
    p3=plot(1:length(idx),vcat(predictor[1,idx[2:end].-1],predictor[1,end]),label="predictor",size=(800,400),dpi=600,
            xlabel="Time step",ylabel="Iterations",title="MG Iterations",ylims=(0,32),xlims=(0,length(idx)))
    # get index of all time steps
    idx = findall(==(0.0),@views(corrector[1,:]))
    # plot inital L∞ and L₂ norms of residuals for the corrector step
    plot!(p1,1:length(idx),corrector[2,idx],color=:2,ls=:dash,label="corrector initial r∞",yaxis=:log)
    plot!(p2,1:length(idx),corrector[3,idx],color=:2,ls=:dash,label="corrector initial r₂",yaxis=:log)
    # plot final L∞ and L₂ norms of residuals for the corrector step
    plot!(p1,1:length(idx),vcat(corrector[2,idx[2:end].-1],corrector[2,end]),color=:2,lw=2,label="corrector r∞")
    plot!(p2,1:length(idx),vcat(corrector[3,idx[2:end].-1],corrector[3,end]),color=:2,lw=2,label="corrector r₂")
    # plot MG iterations of the corrector
    plot!(p3,1:length(idx),vcat(corrector[1,idx[2:end].-1],corrector[1,end]),label="corrector")
    # plot all together
    plot(p1,p2,p3,layout=@layout [a b c])
end


plot_logger("WaterLily.log")
savefig("WaterLily_psolver.png")

the result is this

[codecov]

Codecov Report

Attention: Patch coverage is 53.84615% with 6 lines in your changes missing coverage. Please review.

Project coverage is 93.28%. Comparing base (36dc237) to head (85c78b8).

❗ Current head 85c78b8 differs from pull request most recent head bf3f2f0

Please upload reports for the commit bf3f2f0 to get more accurate results.

Files	Patch %	Lines
src/util.jl	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #135      +/-   ##
==========================================
- Coverage   94.29%   93.28%   -1.02%     
==========================================
  Files          12       12              
  Lines         526      536      +10     
==========================================
+ Hits          496      500       +4     
- Misses         30       36       +6     

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[b-fg]

maybe we could have a plotter.jl file for this stuff and visualization scripts in src/, like a bin of unnecessary utils. Or call it nonutils.jl, even though this does not need to live on src/ but on ext/ which is triggered when loading Plots.jl.

[weymouth]

Yes, that's should not go in src, but in examples or ext.

[marinlauber]

I have added the logger as an extension (via Plots). This means that the examples/TwoD_plots.jl file is now deprecated. I have modified examples/TwoD_circle.jl to show how this looks now. If we decide to go this route for the Plotting utils, I can do the same with Makie for 3D plots and update all the examples to work.

I also renamed the pressure logger example to examples/TwoD_circle_pressure_monitor.jl.