| \( \dot{V} \) | Rate of change in volume |
| \( Q_{i} \) | Flow rate into a volume |
| \( Q_o \) | Flow rate out of a volume |
| \( Q \) | Volumetric flow rate. |
| \( \delta \) | Nonlinear velocity profile correction factor |
| \( \delta \) | Correction factor |
| \( C_1 \) | Arbitrary constant |
| \( \delta'=\delta+1 \) | The modified correction factor |
| \( Z_c^f \) | Characteristic impedance for a forward traveling wave |
| \( Z_c^b \) | Characteristic impedance for a backward traveling wave |
| \( \rho_{w} \) | Density of vessel wall |
| \( \tau_w = \tau_{rz}\vert_{r=r_i} \) | Wall shear stress |