enmodes GmbH engineering modeling design Second Heart Report July 12, 2018 Contact details Dr. Fiete Böhning Head of Engineering Services boehning@enmodes.de +49 (0)241 41251073 +49 (0)176 78013798 enmodes GmbH Wilhelmstraße 38 52070 Aachen Germany www.enmodes.de engineering, modeling, design
Overview of the device CAD geometry provided by Second Heart Impeller diameter: 13.5 & 14.5 mm Open stent (outer) diameter: 22.86 mm 1
Volume extraction Tube around the device Tube diameter: 22.86 mm Extracted fluid volume for flow simulations 2
Boundary conditions Flow Inlet (L/min): 3.5, 4.5 & 5.5 Impeller Speeds (rpm): 7500, 10500 & 15000 Non-Newtonian Blood Model Full 3D simulation Inlet Outlet 3
Analysis Results Impeller 13.5 Impeller 14.5 RPM 15000; average increase in pressure head 31% RPM 10500; average increase in pressure head 40% RPM 7500; ; average increase in pressure head 66% P = Pressure outlet Pressure inlet 4
General observations Large back flow whirls above the impeller blades reduces the efficiency 5
General observations Continuous back flow along the impeller shaft reduces the efficiency 6
General observations (Impeller 14.5 mm) High velocity and low pressures around the blade tip potentially unnecessary high shear stresses Pressure Velocity 7
Comparison of Impellers Impeller 13.5 mm Impeller 14.5 mm 8
Comparison of Impellers Impeller 13.5 mm Impeller 14.5 mm 9
Impeller 14.5 mm 10
Flow simulation Flow 3.5 L/min at 10500 rpm Plane 2 11
Flow simulation Flow 4.5 L/min at 10500 rpm Plane 2 12
Flow simulation Flow 5.5 L/min at 10500 rpm Plane 2 13
Velocity and Streamlines Flow 3.5 L/min at 7500 rpm 14
Velocity and Streamlines Flow 4.5 L/min at 7500 rpm 15
Velocity and Streamlines Flow 5.5 L/min at 7500 rpm 16
Velocity and Streamlines Flow 3.5 L/min at 10500 rpm 17
Velocity and Streamlines Flow 4.5 L/min at 10500 rpm 18
Velocity and Streamlines Flow 5.5 L/min at 10500 rpm 19
Velocity and Streamlines Flow 3.5 L/min at 15000 rpm 20
Velocity and Streamlines Flow 4.5 L/min at 15000 rpm 21
Velocity and Streamlines Flow 5.5 L/min at 15000 rpm 22
Comparison of Flow: 3.5, 4.5 & 5.5 L/min at 10500 rpm Back flow whirls are almost the same for all flow rate for a constant impeller speed. 23
Comparison of Speed: 7500, 10500 & 15000 rpm at 4.5 L/min Back flow whirls increases with increase in impeller speed for a constant flow rate. 24
Impeller 13.5 mm next slides are as sent in the previous report 25
General observations (Impeller 13.5 mm) High velocity and low pressures around the blade tip potentially unnecessary high shear stresses Pressure Velocity 26
Flow simulation Flow 3.5 L/min at 10500 rpm Plane 2 27
Flow simulation Flow 4.5 L/min at 10500 rpm Plane 2 28
Flow simulation Flow 5.5 L/min at 10500 rpm Plane 2 29
Velocity and Streamlines Flow 3.5 L/min at 7500 rpm 30
Velocity and Streamlines Flow 4.5 L/min at 7500 rpm 31
Velocity and Streamlines Flow 5.5 L/min at 7500 rpm 32
Velocity and Streamlines Flow 3.5 L/min at 10500 rpm 33
Velocity and Streamlines Flow 4.5 L/min at 10500 rpm 34
Velocity and Streamlines Flow 5.5 L/min at 10500 rpm 35
Velocity and Streamlines Flow 3.5 L/min at 15000 rpm 36
Velocity and Streamlines Flow 4.5 L/min at 15000 rpm 37
Velocity and Streamlines Flow 5.5 L/min at 15000 rpm 38
Comparison of Flow: 3.5, 4.5 & 5.5 L/min at 10500 rpm Back flow whirls decrease with increase in flow rate for a constant impeller speed. 39
Comparison of Speed: 7500, 10500 & 15000 rpm at 4.5 L/min Back flow whirls increases with increase in impeller speed for a constant flow rate. 40
Summary The current study was conducted for an impeller with blade diameters of 13.5 & 14.5 mm, in a tube with the same outer diameter as that of the open stent, i.e. 22.86 mm. Simulations were carried out for constant flow conditions. Comparison of the two impellers: In general, the pressure head developed by the bigger 14.5 mm impeller is better than that of the 13.5 mm impeller. The local hydraulic behaviour of the impellers are similar. General observations (presented in earlier report): The current design of the Second Heart implantable device results in large back flows around the impeller reducing the efficiency of the device. It also has a potential for unnecessary high shear stresses around the impeller blades. The current analysis also does not provide any indicators for the device effectiveness in human anatomy with respect to pathological conditions, pulsatile flow conditions, device placement, etc. Further analysis & design optimization are needed to improve the device performance and its blood compatibility. 41