# Vary volume fraction of the two species

Here we demonstrate how varying the volume fraction of two different species of particles changes the effective wave speed and attenuation.

## Define the material

using EffectiveWaves

# for fixed total volume fraction
background = Acoustic(3; ρ = 1.0, c = 1.0) # 3 for a 3D material.

gas_particle = Particle(Acoustic(3; ρ = 0.3, c = 0.3), 0.5) # 0.5 is the radius
solid_particle = Particle(Acoustic(3; ρ = 1000.0, c = 1000.0), 1.5)

## Calculate how the wavenumbers change when varying the volume fractions

ωs = LinRange(0.01,0.5,200)

N=5
volumefraction = 0.1
vols = LinRange(0.0,volumefraction,N)

ks_arr = map(1:N) do i
sp1 = Specie(gas_particle; volume_fraction = vols[i])
sp2 = Specie(solid_particle; volume_fraction = volumefraction-vols[i])
[ wavenumber_low_volumefraction(ω, background, [sp1,sp2]) for ω in ωs]
end

speeds = [ ωs ./ real(ks) for ks in ks_arr]
attenuations = imag.(ks_arr)

## Plot the results

labs = reshape( map(v -> "void vol = \$(Int(round(100*v)))%",vols),1, length(vols));
p1 = plot(ωs, speeds,
labels=labs,
ylabel="wave speed (m/s)" ,xlabel="frequency"
);
p2 = plot(ωs, attenuations,
labels=labs, xlabel="frequency", ylabel="attenuation (1/m)");
plot(p1,p2,layout=(2,1))