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Description
Consider the following example
Example
import pandapipes as pp
def main():
net = pp.create_empty_network("network", fluid="lgas")
pp.create_junctions(net, nr_junctions=2, pn_bar=1, tfluid_k=300)
pp.create_pipe_from_parameters(net, from_junction=0, to_junction=1, length_km=0.1, diameter_m=0.2)
pp.create_ext_grid(net, junction=0, p_bar=6)
pp.create_sink(net, junction=1, mdot_kg_per_s=6)
pp.pipeflow(net, mode="hydraulics", friction_model="colebrook")
print(net.res_pipe)
if __name__ == "__main__":
main()Result in 0.9.0
v_from_m_per_s v_to_m_per_s v_mean_m_per_s p_from_bar p_to_bar \
0 41.008797 43.510454 42.211015 6.0 5.602638
t_from_k t_to_k mdot_from_kg_per_s mdot_to_kg_per_s vdot_norm_m3_per_s \
0 300.0 300.0 6.0 -6.0 8.246366
reynolds lambda normfactor_from normfactor_to
0 3.160386e+06 0.01971 0.15623 0.16576
Result in 0.10.0
v_from_m_per_s v_to_m_per_s v_mean_m_per_s p_from_bar p_to_bar \
0 37.320712 39.376898 38.312616 6.0 5.639141
t_from_k t_to_k mdot_from_kg_per_s mdot_to_kg_per_s vdot_norm_m3_per_s \
0 300.0 300.0 6.0 -6.0 7.504737
reynolds lambda normfactor_from normfactor_to
0 3.160386e+06 0.019722 0.15623 0.164837
As you can see the velocity is drastically changed. Is this intentional? Could this PR #597 be a velocity changer?
I used velocity to calculate the Reynolds number by hand using this formula:
, where T is the initial temperature
The formula above in Python
T = 300
Re = (
pp.get_fluid(net).get_density(T)
* net.res_pipe["v_from_m_per_s"]
/ net.res_pipe["normfactor_from"]
* net.pipe["diameter_m"]
/ pp.get_fluid(net).get_viscosity(T)
)With version 0.9.0 the Reynolds numbers calculated by pandapipes and by hand matched. With version 0.10.0, however, the Reynolds numbers didn't match. The Reynolds numbers calculated by pandapipes are identical in versions 0.9.0 and 0.10.0
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