Franziska Martens defends her thesis entitled "Manipulating Thermoacoustic Streaming: Measuring the Synergy of Laser-induced Temperature Gradients and Ultrasonic Pressure Fields in Acoustofluidic Microchannels" Friday the 6th of February, 09:00 at hall E:1406.

Link to thesis in LU Research Portal.

In Acoustofluidics, sound pressure waves can cause a force field on the liquid in a microfluidic channel. The forces depend on density and compressibility of the medium as well as the pressure and velocity amplitude of the sound. The forces lead to a steady flow in the bulk of the fluid, namely acoustic streaming. If a localized change in temperature introduces a gradient in compressibility and density, the force landscape changes accordingly. As a consequence, thermoacoustic streaming arises and replaces the acoustic streaming in velocity and shape. In the experiments for this thesis, a laser beam with a diameter of a third of the microchannel's width creates a localized temperature hot spot through absorption of the light, resulting in a temperature gradient.