Particle image velocimetry of a flow at a vaulted wall

Abstract

The assessment of flow along a vaulted wall (with two main finite radii of curvature) is of general interest; in biofluid mechanics, it is of special interest. Unlike the geometry of flows in engineering, flow geometry in nature is often determined by vaulted walls. Specifically the flow adjacent to the wall of blood vessels is particularly interesting since this is where either thrombi are formed or atherosclerosis develops. Current measurement methods have problems assessing the flow along vaulted walls. In contrast with conventional particle image velocimetry (PIV), this new method, called wall PIV, allows the investigation of a flow adjacent to transparent flexible surfaces with two finite radii of curvature. Using an optical method which allows the observation of particles up to a predefined depth enables the visualization solely of the boundary layer flow. This is accomplished by adding a specific dye to the fluid which absorbs the monochromatic light used to illuminate the region of observation. The obtained images can be analysed with the methods of conventional PIV and result in a vector field of the velocities along the wall. With wall PIV, the steady flow adjacent to the vaulted wall of a blood pump was investigated and the resulting velocity field as well as the velocity fluctuations were assessed.

In Vitro Study of Near-Wall Flow in a Cerebral Aneurysm Model with and without Coils

“…22 The term "Wall-PIV" is used because of the similarity of the proposed technique to PIV. The basic principles of the PIV technique are well described by Adrian.…”

“…23 In this study, we used Wall-PIV as a pure visualization technique, and the principles are briefly described below. A more detailed description of the proposed technique can be found in Kertzscher et al 22 and Berthe et al 24 The Wall-PIV technique uses reflecting particles, which are added to the fluid as tracers, then illuminated, and recorded with a digital camera. The illumination is realized with diffuse monochromatic light illuminating the model from the camera side.…”

Experimental and Numerical Investigation of an Axial Rotary Blood Pump

“…By knowing the tangential velocity components at the measured wall normal height and the assumption of no‐slip at the wall, WSS can be estimated. A more detailed description including a validation of this measurement technique can be found in the work of Berthe et al , Kertzscher et al , and Affeld et al .…”

Dual streamline seeding

“…9 for the validation of a CFD solution with experimental data. A transparent silicon model of a cerebral aneurysm was used for the experimental flow, particle traces of the near-wall-flow were recorded in a gray-scale image with the wall PIV technique by Kertzscher et al [6]. The same geometry and flow condition was used for the CFD computation.…”