# A Dual Frequency Ultrasonic Cleaning Tank Developed by Transient Dynamic Analysis
## 4 Result and Discussion
### Scheme to Develop Dual Frequency UCT
Similar to the previous figure, the -max and +max values of acoustic pressure occurred during 643.75 and 656.25 us, respectively with different distribution patterns from Figure 12. Once we compared the distribution of the +max and -max values between model A in Figure 12 and model B in Figure 13, we discovered that model A gave the higher acoustic pressure level and had better distribution throughout the space of the tank than model B. From all of these reasons, we are confident that model A is better than model B. The animations supported the discussion in Figures 12 and 13 are ModelA_S1.mp4 and ModelB_S1.mp4 attached in the supplementary material. For further investigation, Figure 14 shows the acoustic pressure distributions in S\({}_{2}\) during the time when -max and +max values occurred for (a) model A and (b) model B. The red and blue parts represent positive and negative values of acoustic pressure which had values higher than 25 kPa. We found that these acoustic pressure levels give rise to power concentration values of 9-10 W/liter [30] which is sufficient for cleaning electronic parts, gems, and jewelry in factories. Therefore, these criteria were set for considering the UCT's cleaning performance. From the figure, it is noticeable that during the 0-750 us range, model A gave -max and +max values of acoustic pressure at 608.93 and 697.32 us, respectively. Meanwhile, model B did so at 521.43 and 545.54 us, respectively. When Figure 14a,b was compared, we found that in model A, apart from giving such higher -max and +min values of acoustic pressure, it also had wider area (red and blue) which is more suitable for cleaning than model B. From this, it would be easier to design a jig or a handle to hold the object. It would also be able to clean objects better as well. We also found that for all vertical surfaces in UCT such as S\({}_{1}\) and all horizontal areas such as S\({}_{2}\), the -max or +min values would occur simultaneously. This matter leads to the fact that in vertical and horizontal arrangements, the -max or +min values of acoustic pressure would not occur at the same time. This result could be used to analyze and design a jig for \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**Model**} & \multicolumn{1}{c}{**Position**} & \multicolumn{1}{c}{**NPS**} & \\  & **28 kHz** & & **40 kHz** \\ \hline \multirow{2}{*}{A} & P\({}_{1}\) & 0.48 & 0.70 \\  & P\({}_{2}\) & 0.82 & 0.26 \\ \hline \multirow{2}{*}{B} & P\({}_{1}\) & 0.53 & 0.32 \\  & P\({}_{2}\) & 0.35 & 0.39 \\ \hline \multirow{2}{*}{28 kHz (in Figure 2b)} & P\({}_{1}\) & 1.00 & - \\  & P\({}_{2}\) & 0.40 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Normalized power spectrum at positions P\({}_{1}\) and P\({}_{2}\) calculated by FFT. holding the object that will be cleaned. After considering all results from Figures 11-14, we found that they were consistent. This indicated that model A was more suitable as a model for the commercial production rather than model B. It also confirmed that the NPS could reasonably signify the UCT's cleaning performance. We also used the TDA to simulate the acoustic pressure for the simple tanks with three pieces of 28, 40, and 60 kHz transducers. The simulation found that it worked fine as well but is not reported in this article due to the limitation of space. Still, it helped to confirm that the TDA could be applied to multifrequency tank designs. Higher ultrasonic frequencies produce smaller cavitation bubbles than lower frequencies; therefore, the UCTs with 28 and 40 kHz produce the cavitation bubble radius during 7-16 \(\upmu\)m [40]. Figure 12: Acoustic pressure distribution in terms of time at S\({}_{1}\) for model A.  
Figure 13: Acoustic pressure distribution in terms of time at S\({}_{1}\) for model B. As mentioned in Section 3.3, the HRA and the TDA could be simulated with the ANSYS software by upgrading it with an additional package called ACT\(\times\)2020R1 [35,36].