A computational study of drug particle delivery through a shock tube

Transdermal powdered drug delivery is a recent concept which has been proposed as an alternative of the conventional drug delivery systems. The idea is to accelerate the drug particles behind a moving shock inside the shock tube so that particles can gain enough momentum to penetrate the outer layer of the skin (stratum corneum) and have a pharmaceutical effect. The drugs are delivered in a powdered form. While delivering the particles to the skin two important issues have to be taken care of. The particles should be delivered with uniform velocity and with spatial distribution. To fulfill these requirements different systems have been tried and tested . Among different systems the contoured shock tube (CST) system is the one to be mentioned. CST system can successfully produce uniform velocity and also with spatial distribution. However, future application of this system demands flexibility and capability to accommodate a wide range of drugs and doses. This paper aims at numerical investigation of particle transportation through the contoured shock tube. Computation fluid dynamics (CFD) has been used to model the flow field and analyze it in details. The unsteady DPM (discrete phase model) is adopted to model the particle transportation. The drug correlation proposed by Igra et al. is used instead of the standard drag correlation to predict the particle movement through the flow filed. The gas and particle dynamics inside the shock tube is closely monitored and analyzed. The effect of different particle features in the transportation process is also investigated.