Pulsatile flow drivers in brain parenchyma and perivascular spaces: a resistance network model study

Table 1 One vessel and two vessel model parameters

Symbol	Description	Baseline value	Simulated range	Source
R _i	PVS inner radius	10 μm	1–29 μm	[4, 13, 21]
R _o	PVS outer radius	30 μm	2–30 μm	[4]
L_PVS	PVS segment length	300 μm	–	[17, 21]
L_PCY	Distance between vessels	200 μm	–	[19]
b	Wave amplitude	0.25 μm	0–0.37 μm	[13]
f	Pulse frequency	5 Hz	–	[14]
–	Wave speed	1 m/s		[24,25,26]
K	Hydraulic conductivity	5.63 × 10⁻¹² m²/(Pa s)	10²–10¹¹ μm³ s/kg	[27]
μ	Dynamic viscosity	0.9 × 10⁻³ Pa s	–	[28, 29]
ρ	Interstitial fluid density	993.2 kg/m³	–	[30]
ϕ	Porosity	0.2		[31]
D*^b	Solute diffusivity	–	10¹–10³ μm²/s	[31, 19]
l ^a	Resistance length	50; 100 μm		Model dependent
h	Resistance height	100 μm		Model dependent
d	Resistance depth	200 μm		Model dependent
R ^PCY_i	Parenchyma inner radius	10 μm		[4]
R ^PCY_o	Parenchyma outer radius	300 μm		Model dependent
η	Pore size	60 nm		[32]
θ	Phase shift	0	0–2π	Model dependent
ξ	Pulsatility ratio	0.80	0–1	[13]

^aR2, R3 in the one vessel model and R6, R8, R9, R10, R11, R13, R15, R16, R17, R18, and R20 in the two vessel model had lengths of 100 μm. All others resistors had lengths of 50 μm except R5, R6, and R7 in the one vessel model which were defined as in Eq. 3
^bD* refers to the effective solute diffusion coefficient in brain tissue

ISSN: 2045-8118