## 4 Results and Discussion  
To eliminate residual air from a porous medium, it is necessary to perform successful molding. The formation of voids due to partial impregnation of resin inside the fibrous reinforcement can lead to failures in the use of the final product [45]. In this sense, geometric optimization is essential because it not only increases productivity by reducing the time of injection, but also enhances the quality of the pieces produced. Thus, the prevention of the formation of voids in the porous medium is a restriction in the analysis and definition of the liquid resin infusion (LRI) process. A reference line was created in the domain to measure filling time (see the horizontal dashed lines in Figure 1a,b, defined by the following points: \(P_{1}\) (\(x_{1}=-0.25\) m, \(y_{1}=0.50\) m) and \(P_{2}\) (\(x_{2}=0.25\) m, \(y_{2}=0.50\) m)). The position of the front line of the resin flow is monitored along this line. When the resin flow completely crosses the reference line, i.e., when the volumetric fraction along the entire line is equal to \(f=1.0\), the infusion process is considered complete. To evaluate the geometric influence of the I-shaped empty channel over the filling infusion time of the resin along the rectangular porous plate, the fraction area inside the domain is analyzed. Simulations performed with different \(L_{0}/H_{0}\) ratios are used to determine the case with lower infusion time for five different fraction areas of the empty channel, \(\phi=0.005\); \(0.01\); \(0.03\); \(0.05\) and \(0.1\). It has been found that the effect of the ratio \(L_{0}/H_{0}\) over filling time (\(t\)) is similar for all investigated fractions \(\phi\). The only exception happened for \(\phi=0.1\) due to the restriction of the geometry in the upper limit of \(L_{0}/H_{0}\), as can be seen in Figure 5. In general, it is noticed that the lowest \(L_{0}/H_{0}\) ratios lead to the best results, i.e., there is a reduction in filling time (\(t\)) when the channel has higher penetration in the \(y\)-direction of the domain. However, the progressive increase of \(L_{0}/H_{0}\) to the upper limit results in a decrease in injection time too. Thus, there is a globally optimized ratio placed in the lowest region of \(L_{0}/H_{0}\) and a local optimized ratio region, placed in the superior limit of the ratio \(L_{0}/H_{0}\) investigated. The worst performance, for almost all cases of \(\phi\), is reached for intermediate ratios of \(L_{0}/H_{0}\). Different behavior is noticed only for \(\phi=0.100\), where there is an almost asymptotic growth of filling time as a function of ratio \(L_{0}/H_{0}\), showing that restriction influences the best shape and effect of geometry over the performance indicator. The results also showed that the best configurations for lower magnitudes of \(\phi\) can have a superior performance than those achieved for intermediate ratios of \(L_{0}/H_{0}\), even for higher magnitudes of \(\phi\). For example, the best configuration obtained for \(\phi=0.01\), (\(L_{0}/H_{0}\))\({}_{\rm o}=0.015\) led to a filling time of \(t_{\rm m}=105.3\) s, which is lower than the filling time reached for several configurations (not optimized) with \(\phi=0.03\); \(0.05\) and \(0.1\). This behavior indicates that geometric rationalization can lead to smaller  
Figure 4: Comparison between the placement of resin flow as a function of time by analytical solution. dimension channels for a performance superior to that reached for larger channels, where geometric configuration is not optimized. The optimal results obtained in Figure 5 for each fraction area, \(\phi\), are compiled in Figure 6a. Figure 6a shows the influence of the ratio between the channel area and the area of the plate (\(\phi\)) on the once minimized filling time (\(t_{\text{m}}\)) for the I-shaped empty channel. Results in Figure 6a indicate that for the largest area fractions (\(\phi\)) of the I-shaped channel, the filling time once minimized (\(t_{\text{m}}\)) increases.