1. What did I gain from my time with REDVA?
Rudolf Hellmuth¹
¹Vascular Flow Technologies, UK.
30/08/2017 1

2. WP4 ReDVA Deliverable
Flow Rig Simulations and Computational Fluid Dynamics
Objectives:
To analyse the flow dynamics inside the vascular grafts with the spiral laminar flow (SLF) technology of vascular flow technology (VFT).
To analyse the flow dynamics inside arteriovenous fistulae using the magnetic resonance imaging (MRI) data from ReDVA.
To develop tools to improve the efficiency and accuracy of vascular CFD analyses.
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3. Analysis of the SLF Inducer
Variation of 5 designs and 14 flow conditions (Re = [100, 200, …, 1500]).
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4. Analysis of the SLF Inducer
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5. Simulation of Patient-Specific Arteriovenous Fistula
ReDVA patients (n = 4) were scanned using two modes of MRI: multi- echo data image combination (MEDIC) and time of flight (ToF).
Proximal flow rates for the artery and vein were obtained from velocity encoding (VENC) of MRI scans.
The image quality between ToF and MEDIC were compared by the differences in predicted haemodynamics caused solely by segmentation differences.
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6. Simulation of Patient-Specific Arteriovenous Fistula
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7. Evaluation of Segmentation Methods for Vascular CFD from Medical Images
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8. Development of Boundary Conditions for Vascular CFD
Lumped models of pressure for the dynamic effects downstream from the outlet.
Examples of models:
Resistive (p = R*Q).
Windkessel (RCR).
Impedance.
Actuators.
[Vignon-Clementel, et al. (2006), Comp. Meth. in Appl. Mech. and Eng. 193 (29-32): ]
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9. CFD inside a Circuit R R p1 = R1 Q1 p2 = R2 Q2 R0 CFD domain
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10. Resistances obtained from average flow rate and average pressure.
Bifurcation of the Aorta into Iliac Arteries
Resistances obtained from average flow rate and average pressure.
Capacitance obtained from characteristic time.
75% narrowing is asymptomatic (no ischemia).
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11. Realistic pressure levels Flow much more evenly distributed.
Left Coronary Arteries
Zero pressure at all outlets
Resistances Calibrated with Area
Realistic pressure levels
Flow much more evenly distributed.
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12. What did I gain from my time with REDVA?
More experience simulating vascular flow.
The ability of comparing physical variations of many simulation cases.
More experience segmenting and manipulating vascular models from medical imaging.
I attended to a number of training workshops and industry fairs.
I’ve learned how to properly couple the boundary conditions of velocity and pressure, which is necessary for predicting flow dynamics inside a pipe network.
I’ve produced relevant data and tools for analysing cardiovascular flows, specially in arteriovenous fistulae.
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