# Aerodynamic Drag Study of the Heat Exchange Equipment with Different Fin Geometries
## 5 Results and Discussion  
The contour of velocity, pressure, and dynamic pressure are given for three variants of orientation of fins in the channel and for a velocity of 2 m/s. All other values were fixed and entered into the data table, as a result of which a graph was constructed. Velocity contours during longitudinal and transverse flow around fins are presented in Figure 5. In case of longitudinal flow, only the plane of the Y-Z contour is shown, since the picture in the X-Z plane at this location is absolutely similar--this is caused by the symmetrical shape of the fins. However, the contours for transverse flow are given for two planes X-Y and X-Z, since in this case, the arrangement of the pattern on the contours is of a different nature and has certain features. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Mesh Resolution** & **3** & **4** & **5** & **6** & **7** \\ \hline number of elements & 25,600 & 68,992 & 222,264 & 598,792 & 1,707,896 \\ \hline drag coefficient & 1.98 & 2.30 & 2.21 & 2.11 & 2.09 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Dependence of drag coefficient from mesh resolution. Velocity distribution contours for the placement of transverse flow of fins (Figure 5d) fully correspond to the results obtained in the study of [PERSON] and [PERSON] with the drop-shaped contour of the low pressure zone immediately behind the nozzle and a pressure increase from the upper and lower parts of the fins [29]. Figure 5: Velocity contour: (**a**) longitudinal flow around the fins from the smaller diameter side (Y-Z plane); (**b**) longitudinal flow around the ribbing from the side of the larger diameter (Y-Z plane); (**c**) transverse flow of fins (X–Y plane); (**d**) transverse flow of fins (X–Z planes). In Figure 6, the pressure contour during longitudinal and transverse flow around the fins is given. Figure 7: Dynamic pressure contour (velocity pressure): (**a**) longitudinal flow around fins from the smaller diameter side (Y–Z plane); (**b**) longitudinal flow around the ribbing from the side of the larger diameter (Y–Z plane); (**c**) transverse flow of fins (X–Y planes); (**d**) transverse flow of fins (X–Z planes). In Figure 7, the contour of dynamic pressure (velocity pressure) during longitudinal and transverse flow around the fins is given. The analysis of the obtained plots allows a qualitative assessment of the character of the aerodynamics of the flow near the fins for three orientations in the channel. In the case of longitudinal flow around the fins with blowing from the smaller diameter side, the maximum velocity values are 2.29 m/s (Figure 5a), the maximum pressure value is 101,327.6 Pa (Figure 6a), and the maximum dynamic pressure value (speed pressure) is 3.44 Pa (Figure 7a). In the case of longitudinal flow around fins with blowing from the larger diameter side, the maximum velocity values are 2.43 m/s (Figure 5b), the maximum pressure value is 101,325.8 Pa (Figure 6b), and the maximum dynamic pressure value (speed pressure) is 3.71 Pa (Figure 7b). In the case of transverse flow around the fins, the maximum velocity values are 2.48 m/s (Figure 5c), the maximum pressure value is 101,327.65 Pa (Figure 6c), and the maximum dynamic pressure value (velocity pressure) is 3.73 Pa (Figure 7c). An important difference between the transverse location of the fins and the longitudinal fins is the difference in the distribution of physical parameters in the main cross-sections, especially the pulsations of velocities and pressures that cause the separation of the flow behind the fins. Turbulence in this case is large-scale, so this orientation of the fins can be considered poorly streamlined. For longitudinal blowing, the geometric shape of the fins is symmetrical, while the ribs are directed in such a way that they form channels that coincide with the direction of the flow and the highly turbulent areas are more local in nature. When comparing the longitudinal orientations, a significant difference in the values of the resistance coefficients was found.