Peripheral arterial occlusive disease (PAD) is prevalent nowadays, especially among senior citizens. Clinically, doctors define the severity of PADs by the degree of narrowing of stenotic lesion. For example, critical stenoses are characterized by over 70% luminal narrowing. The critical stenosis can very often cause turbulence and reduce flow by means of viscous head losses and flow choking. Very high shear stresses near the throat of the stenosis can activate platelets and thereby induce thrombosis, which can totally block blood flow to the heart or brain \[1\]. Therefore, doctors conclusively treat critical stenoses.  However, they are still uncertain about the cumulative effects of multiple subcritical stenotic lesions (i.e., \< 55% luminal narrowing), especially under pulsatile systole condition. In order to accurately and efficiently simulate flow in arteries with multiple sequential stenoses, we have developed a 3D high-order spectral difference (SD) flow solver with local mesh refinement capability. This solver employs high-order curved mesh elements in the vicinity of arterial wall, and thus represents the geometries much more accurate than linear meshes employed in traditional Finite Volume Method solvers, such as ANSYS-Fluent and STAR-CCM. Meanwhile, the local mesh refinement technology dramatically reduces computational cost by distributing more elements in critical regions, such as the post-stenotic region with large recirculation and shear layers. Benchmark numerical tests confirmed that this solver, despite the existence of curved nonconformal meshes due to local mesh refinement, maintains the high-order accuracy of the SD method. We have already used this SD solver and successfully simulated an arterial flow characterized with a single stenosis of 75% narrowing at a freestream Reynolds number of 500. Our preliminary results show that the flow is already turbulent in the post-stenotic region. Furthermore, we have performed simulations past three sequential moderate stenoses of 60% narrowing with steady inflow condition. Flow streamlines in recirculation regions are already indicating turbulence production which originates likely from a strong shear layer which develops between the central jet and the recirculation region. In Reference \[2\], a single moderate stenosis was considered. In the final paper, we will report a careful validation against the simulation results by the Nektar code \[2\] for an arterial flow with one moderate stenosis. New simulation results for one critical stenosis, multiple moderate stenoses, and even multiple critical stenoses from our SD code will be carefully discussed.  

 

 

\[1\] Ku D. Blood flow in arteries. Annu Rev Fluid Mech 1997;79:399 –434

\[2\] VARGHESE, S., FRANKEL, S., & FISCHER, P. (2007). Direct numerical simulation of stenotic flows. Part 1. Steady flow. *Journal of Fluid Mechanics,* *582*, 253-280.


A High-Order Spectral Difference Code With Curved Local Mesh Refinement for Predicting Arterial Flow Through Multiple Sequential Stenoses

Division / Sponsors: 
Pressure Vessels & Piping (PVP)


Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2020/volume/83815

PVP2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.