The volumetric force term (F ) in momentum balance is calculated
from the pressure intensity field I, determined from Eq. 9.
Assuming plane wave approximation F can be expressed by the
following relationship:
F = \(\frac{2\ \alpha}{\ C_{s}}\text{\ I}\) [Eq. 9]
Detail of this derivation can be obtained from (Huang, Holt, Cleveland,
& Roy, 2004).
Where F , \(\alpha,\) Cs and I are
volumetric force, sound attenuation coefficient, sound speed and
intensity, respectively. Solving this with finite element analysis in
COMSOL using the specified boundary conditions (Table 2) and input
parameters (Supplementary table 2) yields the velocity field at each
point of the sonication tube (Fig 7b). Velocity streamline indicates the
direction of fluid flow. The area inside the streamlines are marked
yellow and quantified with ImageJ. (details in supplementary figure 1-5,
table 3- 12)