# Computational Study of Inertial Flows in Helical Microchannels
## 6 Discussion  
The obtained results show us a possibility of sorting cells according to their size in helical channels. The parameters of the channel can be adjusted in order to obtain stabilized positions of the cells situated in a convenient vertical position within the channel cross-section.  
The cell sorting can be obtained by using proper inlets and outlets of the channel, as proposed in Figure 14. The inlets here are two separate tubes, one of them injected a cell-free buffer liquid and leading to the upper part of the circular cross-section above the dashed horizontal line (see Figure 4) that separates the upper and lower stabilized position for the smaller cells. The second inlet tube contains a suspension of cells that should be sorted. This inlet tube leads into the lower part of the helical cross-section below the dashed line. This results in stabilizing the smaller cells in the lower part of the channel. The larger cells can escape from this lower part and become stabilized in the upper part.  
The outlet is composed of two tubes as well. The tube that comes from the upper part of the cross section collects the larger cells, while the tube from the lower part collects the smaller cells.  
A future research direction consists of a modified helix with an elongated cross-section. The distance between the stabilized positions can be augmented by deformation of the original circular cross-section.  
Figure 12: The trajectory of cells for variable values of timestep. Negative values on the x-axis are for the inner wall of the cross-section, and positive values are for the outer wall of the cross-section. (**a**) grid value 2 \(\upmu\)m. (**b**) grid value 1 \(\upmu\)m.  
Figure 13: The trajectory of cells for variable values of spatial grid. Negative values on the x-axis are for the inner wall of the cross-section, and positive values are for the outer wall of the cross-section. (**a**) Timestep value 0.02 \(\upmu\)s. (**b**) Timestep value 0.01 \(\upmu\)s.  
**Author Contributions:** Data curation, K.K.D.; Formal analysis, I.C.; Funding acquisition, I.C.; Investigation, K.K.D.; Methodology, I.C.; Project administration, I.C.; Software, K.K.D.; Supervision, I.C.; Validation, K.K.D.; Visualization, K.K.D.; Writing--original draft, K.K.D.; Writing--review and editing, I.C. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was supported by the Operational Program \"Integrated Infrastructure\" of the project \"Integrated strategy in the development of personalized medicine of selected malignant tumor diseases and its impact on life quality\", ITMS code: 313011V446, co-financed by resources of European Regional Development Fund, and by the Ministry of Education, Science, Research and Sport of the Slovak Republic under the contract No. VEGA 1/0643/17 and by the Slovak Research and Development Agency under the contract No. APVV-15-0751.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Data are contained within the article.  
**Conflicts of Interest:** The authors declare no conflict of interest.