美国爱达荷大学Ralph S. Budwig教授做《Seeing through and around the sediment bed; applying the refractive index matching method to unveil complex hydraulic and hypothetic processes》的报告

河海大学副校长郑金海为Ralph S. Budwig教授颁发证书

Abstract: Optical measurement methods are widely used to obtain fluid velocity whole field results, and in some cases the associated thermal, chemical, and biological fields.  Methods include particle image velocimetry (PIV), laser Doppler velocimetry (LDV), and laser induced fluorescence (LIF).  However, in many applications the fluid flow is around or through solid objects which will block or distort optical access.  Refractive index matching (RIM) was developed (see e.g., Budwig, 1994; Wiederseiner et al., 2011; and Wright et al., 2017) and has been applied to study complex flow in physical models of blood vessels, porous media flows, and complex passages in commercial applications such as nuclear reactors passages or gas turbine blade arrays.

In the past, most RIM studies have used solid material models (typically glass or transparent plastic) that have required hydrocarbon or toxic aqueous solutions to match the refractive index of the solid material.  More recently, hydrogel has be proposed as a soft solid material that may be used for solid models (Weitzman et al., 2014; Dijksman et al., 2017, Harshani et al., 2017, and Rubol et al. 2018), with the advantage that pure water may be used as the working fluid.

In the present presentation, I will review the principles of the RIM method, and go on to discuss emerging physical modelling methods that can use water or water with a small amount of non-toxic solute as the working fluid.  This is opening the door for future studies of flow over and through a simulated sediment bed with the potential to perform fully three-dimensional physical modelling of the fluids dynamics as well as bio-geo-chemical interactions.

Keywords: hyporheic flow; porous media flow; refractive index matching bio-geo-chemical processes; PIV; LIF