def pressure_difference_to_gravity(self, delta_p, length): ''' Converts gravity driven force to equivalent pressure difference ''' from md_statistics import MDStatistics md_statistics = MDStatistics(self.md, self) density = md_statistics.get_density() return delta_p / (length*density*self.md.mass)
def gravity_to_pressure_difference(self, g, length): ''' Converts gravity driven force to equivalent pressure difference ''' from md_statistics import MDStatistics md_statistics = MDStatistics(self.md, self) density = md_statistics.get_density() return g*density*self.md.mass*length
def length_from_knudsen_number(self, knudsen_number): ''' Calculates required density to get a specific Knudsen number through Kn=mean_free_path/length ''' sigma = 1.0 # Diameter from md_statistics import MDStatistics md_statistics = MDStatistics(self.md, self) density = md_statistics.get_density() return 1.0/(sqrt(2.0)*pi*sigma**2*knudsen_number*density)