The origin of many, if not all, vascular diseases can be correlated with endothelial cells (ECs) mechantransduction. The mechanosensory of ECs is strongly linked to the physics of blood flow. CFD models of vascular blood flow can provide insightful information about the hemodynamic environment associated with different vascular disease. Hence, CFD can contribute to the research on ECs mechanotransduction. However, since blood flow is inherently multi-harmonic pulsatile flow and vascular geometry have complex 3D morphology, CFD models require rigorous validation practice in order to ensure that their results are as valuable as they are considered to be.
I would like to discuss the previous efforts conducted to provide consistent, reproducible and physically meaningful validation procedure for CFD models of pulsatile flow for vascular hemodynamics applications. Is there any validation resource available for public access? What would a good and reliable validation database include?
The FDA nozzle benchmark is perhaps one of the best benchmarks available for the validation of CFD codes: https://ncihub.org/wiki/FDA_CFD
In addition there are of course several fluid dynamics benchmarks like flow around a cylinder, Taylor Green Vortex, Lid Driven Cavity etc to name a few. A thorough comparison of CFD method/code to these benchmarks improves confidence on the CFD. However, a mesh convergence study should be performed always when a new application or geometry is used for flow simulations.
Thank you Dr. Kartik Jain for the informative response. I have used many of these validation datasets in my early CFD work on turbulent combustion modeling. However, pulsatile flow is quite different from fully developed flow, especially when it comes to transition to turbulence. The FDA nozzle benchmark is dealing with fully developed flow too.
As to the mesh convergence tests, of course it's a good way to establish benchmark for evaluating the numerical error in a CFD model. Similar to Richardson extrapolation or any of its variants, mesh convergence estimates the error resulting from discretization scheme. Validation, on the other hand, aims at estimating the error resulting from the physical model and assumptions in the governing equation (such as viscosity closure).
Thank you Dr. Khalid M. Saqr. For pulsatile flow the option is to conduct experiments in parallel to simulations for cross-validation. Even after that, when you have flows with different pulsations or if you apply the validated pulsating flow to a different geometry, I wonder how valid the solution would be! I think we should do whatever is possible for validation and rely on verification (grid convergence) for some of the applications.
It seems to me that a rather straightforward setup of a pulsatile flow could already generate very valuable results for validation !
Thank you Prof. C. H. Venner . I wonder if there's a publicly available database that is suitable for this purpose. Given the wide variability of Womersley and Reynolds numbers in the human circulatory system, I think that the validation setup might need to be comprehensive in terms of variables and parameters. Most of the published experimental studies, as to my knowledge, do not reveal sufficient details to allow reproducibility for CFD validation.
I am not fully aware of the recent update on this topic but, as I worked on some years ago, I remember some past papers exist, on 1D models. Not sure if a database (such as like a DNS in a pulsatile channel) is available, see:
Article Direct numerical simulation of stenotic flows, Part 2 : Puls...
There are several issue in such problems, I remember just a couple of that: 1) non-newtonian fluid if the goal is to assess the role of the stress at the wall 2) fully compressible FSI having different Mach numbers.
I suggest to check the Annual Review of Fluid Mechanics,
https://www.google.com/search?client=firefox-b-d&q=annual+review+fluid+mechanics+blood+flow
as well as the JFM and PoF journals
Thank you Professor Filippo Maria Denaro
The work of Varghese et al studies mono-harmonic (i.e. sinusoidal) pulsatile flow, which has different regimes and characteristics than multi-harmonic pulsatile flow. In addition, extracting the data from these papers is not a straightforward task. I wonder if there's a publicly-available dataset in a format suitable for this purpose.
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