Source code for baseclasses.problems.FluidProperties

import warnings


[docs]class FluidProperties: """ Parameters ---------- gamma : float (default = 1.4) Set the ratio of the specific heats. Pr : float (default = 0.72) Set the Prandtl number. R : float (default = 287.055 J / kg / K) The specific gas constant. By default we use air. SSuthDim : float (default = 110.55) The Sutherland temperature for Sutherland's Law. muSuthDim : float (default = 1.716e-5) The viscosity at the reference temperature for Sutherland's Law. If you want to directly specify a viscosity for your fluid (e.g., running a case in water), a hack to achieve this is to set `muSuthDim` to the desired viscosity and `T` to `TSuthDim`. By doing so, `mu` will be equal to `muSuthDim`. TSuthDim : float (default = 273.15) The reference temperature for Sutherland's Law. """ def __init__(self, **kwargs): # Check if we have english units: self.englishUnits = False if "englishUnits" in kwargs: self.englishUnits = kwargs["englishUnits"] # Check if 'R' is given....if not we assume air if "R" in kwargs: self.R = kwargs["R"] else: # Universal gas constant # (https://physics.nist.gov/cuu/Constants/) R_universal = 8.3144598 # J / mol / K # Molecular mass of air # (https://www.engineeringtoolbox.com/molecular-mass-air-d_679.html) M_air = 28.9647 # g / mol # Specific gas constant of air in S.I. units R_air = R_universal / M_air * 1000.0 # J / kg / K # Conversion from S.I. to english. Basically the S.I. units are # m^2 / s^2 / K so we need to convert meters to feet and Kelvin to # Rankine m2ft = 0.3048 # official conversion from meters to feet Ra2K = 1.8 # official conversion from Rankine to Kelvin if self.englishUnits: self.R = R_air / Ra2K / m2ft**2 # 1716.574 ft-lbf / slug / R else: self.R = R_air # 287.055 J / kg / K # Check if 'gamma' is given....if not we assume air if "gamma" in kwargs: self.gamma = kwargs["gamma"] else: self.gamma = 1.4 # Check if 'Pr' is given....if not we assume air if "Pr" in kwargs: self.Pr = kwargs["Pr"] else: self.Pr = 0.72 # Sutherland's Law Constants # (https://www.cfd-online.com/Wiki/Sutherland's_law) if "SSuthDim" in kwargs or "muSuthDim" in kwargs or "TSuthDim" in kwargs: if not all(name in kwargs for name in ("muSuthDim", "muSuthDim", "TSuthDim")): warnings.warn( "One or more constant for Sutherlands law might be missing!\ Make sure to provide all three!" ) if "SSuthDim" in kwargs: self.SSuthDim = kwargs["SSuthDim"] else: self.SSuthDim = 110.55 if "muSuthDim" in kwargs: self.muSuthDim = kwargs["muSuthDim"] else: self.muSuthDim = 1.716e-5 if "TSuthDim" in kwargs: self.TSuthDim = kwargs["TSuthDim"] else: self.TSuthDim = 273.15
[docs] def updateViscosity(self, T): """ Compute the dynamic viscosity using Sutherland's Law """ # calculate the dynamic viscosity if self.englishUnits: T /= 1.8 self.mu = self.muSuthDim * (T / self.TSuthDim) ** 1.5 * (self.TSuthDim + self.SSuthDim) / (T + self.SSuthDim) if self.englishUnits: self.mu /= 47.9