Measurements on the Mixing of a Passive Scalar in a Turbulent Pipe Flow Using Dpiv and Lif.

Abstract

Turbulent mixing is a point of research with many applications in science and engineering. Points of interest are maximum concentration levels in turbulent mixing flows and chemical reactions. The mixing process can be described as the interaction between a flow field and a concentration field. The flow field follows from the Navier-Stokes equation, and is in many cases independent of the concentration field, whereas mass transport can be described with help of Ficks law. In the case of a time averaged steady and axisymmetric flow field, the Reynolds decomposed equation for the concentration field, only contains two cross correlation terms, that only include radial and axial velocity components and spatial derivatives. These two velocity components can be measured with Particle Image Velocimetry [1], whereas the concentration field can be measured with Planar Laser Induced Fluorescence [2]. In our experiment these two techniques are combined and applied simultaneously to a steady and axisymmetric turbulent pipe flow. Such simultaneous measurements of both the velocity field (using Particle Image Velocimetry) and the concentration field (using planar Laser Induced Fluorescence) in a plane through the pipe axis enables us to measure the full velocity-concentration correlation tensor. The results will be compared with the results of a DNS and will be used for validation of PDF-models.KeywordsParticle Image VelocimetryDirect Numerical SimulationConcentration FieldDigital Particle Image VelocimetryPlanar LaserThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.