Simulations of transient shock motion within a biological contoured-shock-tube system

This study is motivated by the author’s interest in developing needle-free powdered vaccine/drug delivery systems. One system configuration is called the Contoured Shock Tube (CST). Of great importance is the behaviour of a transonic gas flow with a strongly nonlinear starting process, which accelerates powdered vaccines in micro-form to a sufficient momentum to penetrate the outer layer of human skin or mucosal tissue. In this paper, an established Modified Implicit Flux Vector Splitting (MIFVS) solver for the Navier–Stokes equations is extended to numerically study these transient transonic gas flows. A low Reynolds number k–ϵk–ϵ turbulence model, with the compressibility effect considered, is integrated into the MIFVS solver to predict the turbulent structures and interactions with inherent shock systems. The MIFVS is first calibrated for NASA validation case, NPARC, and the resulting flow characteristic are compared with experimental date and simulations published. The MIFVS calculation with the modified k–ϵk–ϵ model shows the best agreement. Subsequently, the MIFVS is applied to model the transient gas flow within a biolistic CST prototype. Comparison with experimental pressure traces shows the MIFVS captures gas flow mechanics with more accuracy than calculations with a commercial code (Fluent). This illustrates that the MIFVS is well-suited to model the strongly nonlinear fluid dynamics associated with the CST biolistic particle delivery system.