Fig. 9. Concentration distribution of Ca²⁺ in a simulation of the advection-electrodiffusion of two ionic species interacting with a moving elastic membrane.

The upper panels show the Ca²⁺ concentration distribution on the composite grid at time t = 0.025 ms (left) and at t = 0.225 ms (right). The lower panels show Ca²⁺ concentration profiles through the center of the domain. In each of these lower panels, the dotted curve shows the concentration profile at t = 0.025 ms, and the solid curve shows the concentration profile at t = 0.225 ms. In the lower left panel the concentrations at the two times are plotted as functions of x for fixed y, and in the lower right panel they are plotted as functions of y for fixed x. As the elliptical membrane becomes more circular, the concentration profiles shift accordingly. The membrane is only slightly permeable to Ca²⁺. Note the buildup of Ca²⁺ adjacent to the membrane, which contributes to the space-charge layer.