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bulk concentration
Posted 28 oct. 2015, 05:33 UTC−4 Fluid & Heat, Chemical Reaction Engineering, Studies & Solvers Version 4.4 1 Reply
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Hi
I am working with a 2D axisymmetric geometry of the arterial wall. I am solving transport of diluted species (time dependent).
I would like to compute and represent the partitioning coefficient (k), defined as the tissue concentration at equilibrium normalized by the bulk concentration (k=cT/c_bulk), because I am simulating a test where the arterial wall is incubated in a drug solution at several bulk concentrations for 60 hours.
I do not understand well the concept of "bulk concentration". I know that the tissue concentration is a time dependent concentration, but is the "bulk concentration" a time dependent concentration or is it a constant value??
Thanks in advance,
Javier
I am working with a 2D axisymmetric geometry of the arterial wall. I am solving transport of diluted species (time dependent).
I would like to compute and represent the partitioning coefficient (k), defined as the tissue concentration at equilibrium normalized by the bulk concentration (k=cT/c_bulk), because I am simulating a test where the arterial wall is incubated in a drug solution at several bulk concentrations for 60 hours.
I do not understand well the concept of "bulk concentration". I know that the tissue concentration is a time dependent concentration, but is the "bulk concentration" a time dependent concentration or is it a constant value??
Thanks in advance,
Javier
1 Reply Last Post 28 oct. 2015, 06:44 UTC−4
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Posted:
9 years ago
Partition coefficient is the ratio of the equilibrium concentrations between two phases. Bulk concentration is usually considered either as the value in the bulk (i.e. sufficiently far from surfaces) of the solution or as an initial value if mass transport is emptying the volume.
Partition coefficient is not time dependent; actually it is used as the boundary condition, i.e. if the concentration in the blood stream at the artery wall is Cs, the corresponding value in the artery side is k*Cs, unless some other condition prevails, like kinetically limited flux.
Thinking of your problem, the concentration in the artery after incubation is an initial value, but the concentration will be changing throughout, and talking about bulk concentration is rather meaningless.
BR
Lasse
Partition coefficient is not time dependent; actually it is used as the boundary condition, i.e. if the concentration in the blood stream at the artery wall is Cs, the corresponding value in the artery side is k*Cs, unless some other condition prevails, like kinetically limited flux.
Thinking of your problem, the concentration in the artery after incubation is an initial value, but the concentration will be changing throughout, and talking about bulk concentration is rather meaningless.
BR
Lasse