1. The problem statement, all variables and given/known data The following equation is presented in my textbook, with very little context and J is simply described as the "trans-membrane fluid flux, which can be modeled by using Darcy’s law." Typically in this bioseparations class, when we discuss permeate flux, it is a unit volume per (unit area*unit time), so L*m^-2*s^-1. However, in this case, the dimensions don't really seem to match up. 2. Relevant equations 3. The attempt at a solution p is the pressure difference across the membrane, for which I used pascals σ is a dimensionless rejection coefficient π is the osmotic pressure, also in pascals μ is the viscosity given in cP, but I converted to Pa*s Rm and Rp are appropriate resistivity values given in units of m^-1 So a dimensional analysis shows that the units of J are m/s, which does not represent the permeate flux. My ultimate goal is to calculate J in order to solve for the volumetric flow rate out of the membrane so that I can do a material balance for the system and model the concentration as a function of time.