## 3 Results  
When the dripping speed is adjusted to less than 10 drops/min, the dripping speed is not constant and drops of considerably different sizes are produced. This problem is not observed at dripping speeds of 10 drops/min or more. Therefore, experiments are developed with dripping speeds of at least 10 drops\(\cdot\)min\({}^{-1}\). The dripping speed of drop sizes increases until a certain critical value is reached, after which the drops become smaller as the dripping speed increases until a water jet is formed. The maximum dripping speed is determined only for drops generated using 16-25G needles due to the manufacturer's proposed limitation for a DCLS to count drops at a speed over 360 drops\(\cdot\)min\({}^{-1}\). The maximum dripping speed for drops generated by 27G, 30G, and 32G needles is limited by the ability of the water pump to generate sufficient water pressure in the hydraulic system, with limitation values of 349, 279, and 233 drops\(\cdot\)min\({}^{-1}\), respectively (Figure 2a). Water pressure in the hydraulic system of the simulator is determined by measuring the difference in the water level on the left and right sides of the pressure gauge (Figure 1c). The relation between the drop diameter and dripping speed for different needles is described by a polynomial distribution of 3 rd degree and coefficient of determination (R\({}^{2}\)) ranging from 0.74 to 0.90 (Table 2), which indicates strong relations. With a reduction in needle diameter, the dripping speed at which d Max is reached decreases with a trend described by the equation y = 0.185x\({}^{0.50}\) and R\({}^{2}\) = 0.91 (Figure 2a). The relation between the water pressure and dripping speed for different needle diameters is described by a linear distribution (Table 3). Decreasing the diameter of needles leads to a less sensitive water pressure change due to increasing flow resistance when water passes through the needle with a trend described by the power equation y = 152611884.58x\({}^{-2.60}\) and R\({}^{2}\) = 0.86 (Figure 2b). The relations between drop diameters d Avr to OD Nom are determined by power and logarithmic regression equations and corresponding coefficients of determination. These relations can also be used for the needles excluded from the measurement (10-15G, 17G, 24G, 26G, 28G, 29G, 31G, 33G, and 34G) (Figure 3). The values for the coefficients of determination indicate a very strong relation for all drop diameter-to-dripper diameter relations (Table 2). The relation of d Avr vs. ODNom All is strong for both the power and logarithmic regression equations (Figure 3). Based on known values of drop sizes, falling heights, and achieved velocities, it is possible to estimate the achieved kinetic energy, an important factor for the drop erosivity of rainfall simulators (Equation (1)). Drop velocities are estimated using the [23] model for heights where the drops have achieved 50%, 75%, 90%, 95%, or 99% of their terminal velocity of fall. For the drop diameters ranging between 1.00 and 4.99 mm, highly related polynomial distributions are established for different percentages of their terminal velocities (Figure 4b), the height necessary to achieve them (Figure 4a), and their KE (Figure 4c). Figure 2: Drop diameters as a function of the dripping speed (intensity) for (**a**) different hypoderm needle sizes (16–32G), and (**b**) water pressure as a function of the dripping speed. The red and blue dots represent drop diameters, respectively, at (**a**) d 10 and d Max and (**b**) a water pressure of h 10 and h Max. Red dotted lines represent the power relation of the dripping speed to the maximal drop sizes (Power (d MAX)) and corresponding water pressure (Power (h MAX)). The upper pressure gauge limit is marked with a solid red horizontal line. Note: code colors are similar to those proposed by ISO 6009:2016. The water pressure for a 32G needle is not possible to measure by a simulator pressure gauge, and so it is not presented.