On investigating the flow through an axisymmetric channel with sudden changes in geometry

The paper presents the authors first experience in the complementary use of the CFD and PIV methods for the investigation of a steady flow of an incompressible fluid through a successive sudden contraction (diameters ratio 4:1) and expansion (diameters ratio 1:2). The investigation of this flow was chosen by the authors as a test case for an assessment of the capability of a standard PIV system to make accurate measurements of the 2D velocity field. With this aim in view, in a first step of the study the flow was investigated by numerical simulations using the CFD code FLUENT, in order to map the velocity field and to identify the zones covered by recirculation flow. An experimental set-up was built and PIV investigations were conducted for validating the numerical simulation results. It was observed that there currently exist important technical limitations of the experimental setup in assessing the velocities close to the walls, and implicitly affecting the possibility of validating the results of the numerical simulation. That is why, based on the PIV investigation, at the current stage of the study the authors can only advance qualitative observations and identify possible solutions to upgrade the PIV setup

On investigating the flow through an axisymmetric channel with sudden changes in geometry

The paper presents the authors first experience in the complementary use of the CFD and PIV methods for the investigation of a steady flow of an incompressible fluid through a successive sudden contraction (diameters ratio 4:1) and expansion (diameters ratio 1:2). The investigation of this flow was chosen by the authors as a test case for an assessment of the capability of a standard PIV system to make accurate measurements of the 2D velocity field. With this aim in view, in a first step of the study the flow was investigated by numerical simulations using the CFD code FLUENT, in order to map the velocity field and to identify the zones covered by recirculation flow. An experimental set-up was built and PIV investigations were conducted for validating the numerical simulation results. It was observed that there currently exist important technical limitations of the experimental setup in assessing the velocities close to the walls, and implicitly affecting the possibility of validating the results of the numerical simulation. That is why, based on the PIV investigation, at the current stage of the study the authors can only advance qualitative observations and identify possible solutions to upgrade the PIV setup

Experimental investigations of the steady flow through an idealized model of a femoral artery bypass

The present paper presents the steps taken by the authors in the first stage of an experimental program within a larger national research project whose objective is to characterize the flow through a femoral artery bypass with a view to finding solutions for its optimization. The objective of the stage is to investigate by means of the PIV method the stationary flow through a bypass model with an idealized geometry. A bypass assembly which reunites the idealized geometry models of the proximal and distal anastomoses, and which respects the lengths of a femoral artery bypass was constructed on the basis of data for a real patient provided by medical investigations. With the aim of testing the model and the established experimental set-up with regard to their suitability for the assessment of the velocity field associated to the steady flow through the bypass, three zones that can restore the whole distal anastomosis were PIV investigated. The measurements were taken in the conditions of maintained inflow at the bypass entry of 0.9 l / min (Re = 600). The article presents comparatively the flow spectra and the velocity fields for each zone obtained in two situations: with the femoral artery completely occluded and completely open