Add Buckingham pi tests

src/systems/validation.jl

@@ -279,23 +279,23 @@ function check_units(eqs...)
 end
 all_dimensionless(states) = all(x -> safe_get_unit(x, "") in (unitless, nothing), states)
 
-using DynamicQuantities: @us_str
-const UNITLESS_UNIT = us"1"
+using DynamicQuantities: @us_str, expand_units, DynamicQuantities, SymbolicDimensions
+const UNITLESS_UNIT = DynamicQuantities.Quantity(1, SymbolicDimensions)
 const UNITLESS_SI = expand_units(UNITLESS_UNIT)
-const N_UNIT_DIMS = nfields(dimension(UNITLESS_SI))
+const N_UNIT_DIMS = nfields(DynamicQuantities.dimension(UNITLESS_SI))
 function _get_unit(x)
  getmetadata(ModelingToolkit.unwrap(x), ModelingToolkit.VariableUnit, UNITLESS_UNIT)
 end
 
 function buckingham_pi(vals)
  us = _get_unit.(vals)
- M = [convert(Rational, getfield(dimension(expand_units(u)), p))
+ M = [convert(Rational, getfield(DynamicQuantities.dimension(expand_units(u)), p))
  for u in us, p in 1:N_UNIT_DIMS]
  s = lcm(denominator.(M))
  Mt = convert.(Int, isone(s) ? M' : M' * s)
  coeffs = ModelingToolkit.nullspace(Mt)
  for c in eachcol(coeffs)
  c .= c .÷ gcd(c)
  end
- permutedims(prod(vals .^ coeffs, dims = 1))
+ vec(prod(vals .^ coeffs, dims = 1))
 end

test/units.jl

@@ -197,3 +197,22 @@ maj2 = MassActionJump(γ, [I => 1], [I => -1, R => 1])
 maj1 = MassActionJump(2.0, [0 => 1], [S => 1])
 maj2 = MassActionJump(γ, [S => 1], [S => -1])
 @named js4 = JumpSystem([maj1, maj2], t, [S], [β, γ])
+
+using DynamicQuantities: @us_str
+vals1 = @variables begin
+ ρ, [unit = us"g/m^3"]
+ μ, [unit = us"g/m/s"]
+ u, [unit = us"m/s"]
+ ℓ, [unit = us"m"]
+end
+
+vals2 = @variables begin
+ ℓ, [unit = us"m"]
+ g, [unit = 9.8us"m/s^2"]
+ m, [unit = us"g"]
+ T, [unit = us"s"]
+ v, [unit = us"m/s"]
+ θ
+end
+@test isequal(ModelingToolkit.buckingham_pi(vals1), [μ / (u * ρ * ℓ)])
+@test isequal(ModelingToolkit.buckingham_pi(vals2), [g * (T^2) / ℓ, v^2 / (g * ℓ), θ])