Analysis of Rotating Flow Around a Growing Protein Crystal

We consider the problem of steady flow around a growing protein crystal in a medium of its solution in a normal gravity environment. The whole flow system is assumed to be rotating with a constant angular velocity about a vertical axis which is anti-parallel to the gravity vector. Convective flow takes place due to the solute depletion around the growing crystal which leads to a buoyancy driven flow. Such convective flow can produce inhomogeneous solute concentration, which subsequently generate non-uniformities in the crystal’s structure finalizing lower quality protein crystal. Using scaling analysis within a diffusion boundary layer around the crystal, we estimate the magnitude of the convective flow velocity and other dependent variables of the flow system for cases of weak, moderate and strong rotation and either strong or weak buoyancy. We find, in particular, that for moderate rate of rotation, convective flow is weakened significantly as the rotation rate increases. This result may be of interest for production of high quality protein crystal since the effect of the convective flow around the growing protein crystal is found to be weakened significantly by the rotational constraint