code: def channel_n(self):
          
          min_hydraulic_W =\
              np.amax(np.array([1, (self.max_W/self.W_min_HS_ratio).to(u.dimensionless)])) * self.W_min_HS_ratio
          return 2*np.ceil(((self.vol / (min_hydraulic_W * self.downstream_H) +
                             self.ent_tank_L) / (2 * self.max_L)).to(u.dimensionless))
docs: Calculate the minimum number of channels based on the maximum
          possible channel width and the maximum length of the channels.
          Round up to the next even number (factor of 2 shows up twice in equation)
          The channel width must be greater than the hydraulic width that ensure baffle overlap.
          Based on the equation for the flocculator volume
          volume = ([max_L*channel_n] - entrancetank_L)*max_W * downstream_H
          :returns: number of channels
          :rtype: float * dimensionless