טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentJacob Hila Sarah
SubjectCreeping Gas Flows Through Elastic Micro-Channels
DepartmentDepartment of Mechanical Engineering
Supervisor Professor Amir Gat
Full Thesis textFull thesis text - English Version


Abstract

In this work we analyze the propagation of an ideal Newtonian gas into shallow elastic micron-sized channels. At standard atmospheric conditions, pressure-driven gaseous flows within micron-sized configurations involve significant viscous resistance which leads to relatively large pressure drops. As a result, substantial density variations appear which yield ’low- Mach-compressibility’ with negligible inertial effects. In addition, weak rarefaction effects emanating from Knudsen numbers at the range of Kn ≈ 0.01 to ≈ 0.1 yield velocity- and temperature-slip at the solid boundaries.

In this thesis we examine gas flows in two micro-sized configurations: (i) a long micro elastic tube and (ii) a gap bounded by linearly elastic substrates. In both configurations the micro-channel is initially filled with gas at ambient pressure. Isothermal conditions are assumed and linear elastic models are utilized. We introduce unsteady gaseous viscous peeling models within the framework of compliant microfluidic studies, while also extending weakly rarefied, low-Mach-compressible gas flows by the inclusion of both elasticity and unsteady peeling dynamics therein.

The understanding of gaseous viscous-elastic dynamics in micron-scale geometries is of particular relevance due to the widespread use of soft materials such as PDMS in the fabrication of lab-on-a-chip and other gaseous microfluidic devices, biomechanics of respiratory flows, as well as pneumatic soft-robots. Within the field of soft-robotics, while propagation of pressurized gas into elastic channels is commonly used to induce required solid deformations, no models of transient gas dynamics have yet been suggested. The change of channel cross-section due to elastic deformation has also been deemed a useful tool for applications such as flow control mixing and peristaltic pumping.