# Wind Tunnel Test on Windblown Sand Two-Phase Flow Characteristics in Arid Desert Regions
## 3 Experimental Results and Discussion
### Sand Concentration and Sand Transport Rate in the Windblowon Sand Flow Field
It is necessary to make a further quantitative comparison with previous research results based on the physical value of regression coefficients. The values of coefficients \(a\), \(b\), \(A\), and \(B\) at different conditions in Table 2 indicate that the decay curves of sand concentration and sand transport rate are affected by the wind speed and the particle size. If a logarithmic scale is used to express the sand transportrate, the corresponding curves are transformed into straight lines. The coefficient \(1/B\) is the slope of the straight line, which presents the relative decay rate of the sand transport rate at different heights above the ground. The larger the \(1/B\), the more rapidly the sand transport rate decays with height. In the same way, the regression coefficients of the sand concentration profile also apply to corresponding physical meanings and laws. For the convenience of comparison with previous studies, the following focuses on the regression coefficients of sand transport rate under different conditions. Figure 9: _Cont._  
As can be seen from Table 2, the coefficient \(A\) increases with increasing wind speed for all particle sizes, which is consistent with the conclusion proposed by [PERSON] et al. (2018). At the same wind speed, the value of coefficient \(A\) is the largest for mixed sand, followed by fine sand, and the smallest for coarse sand in this study. However, the research conducted by [PERSON] et al. showed that the value of coefficient \(A\) is the largest for fine sand, followed by mixed sand, and the smallest for coarse sand, and the value of coefficient \(A\) for fine sand is obviously larger than our research results ([PERSON] et al., 2018). Predominantly, deviations in the results may be because the research carried out by [PERSON] et al. ignored the turbulence characteristics of the incoming flow ([PERSON] et al., 2018). In fact, the turbulence causes more fine sand to break away from the creeping motion on the bed surface and enter the saltation motion. Then, compared with the uniform sand bed of fine sands, the mixed sand bed is a non-uniform sand bed. The turbulence causes sand particles with different particle sizes to interact and affect each other, thus making it easier for the original stationary sand particles to enter the creeping motion. Additionally, it may follow on from setup parameters, resulting in different similarity parameters affecting windblown sand transport. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Particle Size**} & \multirow{2}{*}{**Wind Speed**} & \multicolumn{3}{c}{\(\rho_{s}\) **(In This Study)**} & \multicolumn{3}{c}{\(q\) **(In This Study)**} & \multicolumn{1}{c}{\(q\) **([PERSON] et al., 2018)**} \\ \cline{3-8}  & **(m/s)** & \(a\) & **1/b** & \(R^{2}\) & \(A\) & **1/B** & \(A\) & **1/B** \\ \hline Coarse & 14.74 & 6.808 & 16.39 & 0.9894 & 0.0200 & 0.163  
The relative decay rate \(1/B\) decreases with the increase in wind speed for all particle sizes, which reveals that at higher wind speed, turbulence makes the sand particles move more violently and makes more sand particles move at a greater height. However, the research carried out by [PERSON] et al. does not reflect this law well [34], and the relative decay rate of fine sand is higher than our research results.