Shockwaves generated in micro tubes without diaphragms: investigation of shock waves and subsequent flows that are generated with high speed valves or ultrashort laser pulses and that are propagating in fluids within micro tubes

• Applicants: Professor Dr. Walter Garen; Professor Dr. Ulrich Teubner
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics ; Fluid Mechanics
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 447894944

Although physics of shock waves and its applications are well investigated in the macroscopic regime, this is not true for the micro regime (macroscopic: shock tubes with a diameter larger than 1 mm up to much more than 1 m; microscopic: tubes or micro channels with a diameter below 1 mm down to 10 micron (or less)). A few years ago, first experiments with shock waves on micro scale opened a new field within physics of shock waves. However, there are only those few experiments. Nevertheless, it has become clear that the theory that is applied for the macro regime, is not generally suitable (or only partly) for the micro regime. Consequently theory must be revised. Moreover, a series of new questions has become important. Even though there is large interest in the community, as a result of the rare available investigations, physics of shock waves on micro scale may be regarded to be still at the beginning. This directly leads to the motivation for the project and it’s goal: this is to obtain a basic physical understanding of the onset and the propagation of shock waves in micro tubes (including details). It may be mentioned that beside the fundamental importance, this will also be of interest for applications, even though they are not direct objectives within the project (possible applications in medicine or biology are needleless vaccine delivery or the transfer of organic materials into cells; in addition, there is a lot of applications within micro fluidics). Actually, within the project it is intended to generate micro shock waves either with a short laser pulse (LIMS method) or with a high speed magnetic valve. The shock waves will be generated in micro channels filled with gases (different pressures will be applied), vapors or liquids as the fluid. The fluid parameters and the changes of state will be investigated contactless by means of optical methods (mostly) and with high temporal and spatial resolution. Of special interest is the influence of wall friction and heat conduction, the onset, propagation and attenuation of the shock waves and the influence of the contact surface. The shock front curvature, the transition between the turbulent and the laminar regime of the supersonic flow are of interest as well and also experiments with “ideal” colliding shock waves and the application of a laser pulse train for shock wave generation. Finally, it is intended to determine if shock wave generation, propagation and detection is possible in significant smaller tubes as before. The acquired results will built an important physical fundament for applications such as micro fluidics, nano technology, medical physics and many other interesting topics.

• DFG Programme: Research Grants