## 2 Experimental Setup
### Mock Circulation Loop and Flow Visualization Setup  
The hydraulic circuit of the bench is shown in Figure 3 and consists of a ventricular assist device (VAD) Sputnik pump [13], an open reservoir, and a Tygon transparent laboratory tube system (Tygon S3 E-3603, Saint-Gobain Performance Plastics, Courbevoie, France) with an internal diameter of \(\frac{1}{4}\) and \(\frac{1}{2}\) inch. VAD \"Sputnik\" is a continuous type rotary blood pump. At a rotation speed of 6800 rpm, the pump provides the necessary range of fluid flow in the circuit from 0.5 to 3 L/min with 0.5 L/min step. Figure 2: Manufacturing process of transparent TCPC model: (**A**) 3D blank, (**B**) transparent plexiglass base with installed fittings and 3D blank, (**C**) finalized TCPC model given with dimensions. An aqueous solution of glycerol (57% distilled water and 43% glycerol by weight) was used as a model fluid. The working fluid density is 1104 kg/m\({}^{3}\), the dynamic viscosity is 0.0035 Pa\(\cdot\)s at 25 \({}^{\circ}\)C. The temperature of the used fluid corresponded to the ambient temperature. During all experiments, the temperature did not vary more than by 0.5 \({}^{\circ}\)C, which apparently does not have a significant effect on the working fluid viscosity. Changes in fluid flow to LPA, RPA, IVC, and SVC were recorded using ultrasonic flow meters (ME-11 PXL Clamp-on Tubing Flowsensors, Transonic System Inc., Ithaca, NY, USA), two modules for recording flow through tubes (TS410 Tubing Flow Module, Transonic System Inc., Ithaca, NY, USA), connected to a multichannel terminal (T402 Multi-Channel Research Console, Transonic System Inc., Ithaca, NY, USA). Hoffmann clamps were used to regulate the fluid flow through IVC and SVC in a proportion of 63%-37%. Four pressure port adapters were inserted into the hydraulic circuit of the bench for the connection of pressure sensors (TruWave disposable pressure transducers, Edwards Lifesciences Corporation, Al bay, CA, USA), which were connected directly at the inlet and outlet of the Fontan connection. A particle image velocimetry (PIV) system was assembled to implement 2D fluid imaging. The motion path was recorded via the high-speed camera FASTCAM Mini AX 100 (Photron Limited, Tokyo, Japan), located perpendicularly to the laser beams. This camera allows us to get 4000 frames per second at a resolution of \(1024\times 1024\) pixels. The used lens was a Nikon 60 mm f/2.8G ED AF-S Micro-Nikkor (Nikon Corporation, Tokyo, Japan). The Fontan surface was illuminated by the DPSS laser (MGL-F- 532, Changchun New Industries Optoelectronics Technology Co., Ltd., Changchun, China)  
Figure 3: Mock circulation loop, where constant flow generated by Sputnik pump. Changes in pressure and flow in LPA, RPA, IVC, and SVC were detected by FSs (flow sensor) and PSs (pressure sensor). The flow direction is shown by arrows. with a wavelength of 532 nm. The laser beam had a Gaussian profile shape. A long wavelength pass filter was installed in front of the camera lens to block the scattered laser radiation. The blood model fluid was seeded with neutral pink microspheres with a diameter of 20 \(\upmu\)m (DiagPol Plain Fluorescent PMMA Particles, Creative Diagnostics, Upton, NY, USA). These particles luminesce in the yellow spectral range and are registered by the camera. The optical scheme (Figure 4) consists of three beam splitters (NP 50:50 Beamsplitter Cube 400-700 nm, Thorlabs, Inc, Newton, NJ, USA), four dielectric mirrors (MRA20- E02-Right-Angle Prism Dielectric Mirror, 400-750 nm, Thorlabs, Inc, Newton, NJ, USA), and four cylindrical lenses (LJ1622L1-A Plano-Convex Cylindrical Lens, f = 25 mm, 350-700 nm, Thorlabs, Inc, Newton, NJ, USA). Cylindrical lenses are equidistant with respect to the TCPC model. In order to illuminate the full side surface of the model, the laser beam was divided into four similar beams. The diameter of the output laser beam was 2 mm.