I. Fill Time for an RTM part $(25\backslash \%)$ You have two equal sized $\backslash ((50\backslash$times $20\backslash$times $2\backslash$mathrm$\{$~cm$\})\backslash )$ but distinctly different performs that you place next to each other along the length direction in a mold cavity of the same width as shown below. The volume fraction is uniform and equal to $\backslash (55\backslash \%\backslash )$ in the entire mold. A thermoset resin of viscosity $\backslash (10\backslash$mathrm$\{$Pa$.$s$\}\backslash )$ is injected using the RTM process at a constant flow rate of $1$ cc per second until the first preform is filled.

How long will it take the flow front to reach the end of the first perform? Find the permeability of the first preform in the flow direction if the inlet pressure Pin is equal to $\backslash (2\backslash$times $10^\{5\}\backslash$mathrm$\{$~Pa$\}\backslash )$ gage when the resin reaches the end of the first preform. At this time you switch the injection from constant flow rate to constant pressure of $\backslash (2\backslash$times $10^\{5\}\backslash$mathrm$\{$~Pa$\}\backslash )$ gage. It takes the flow front $4000$ seconds from the start of the experiment to reach the end of the second perform and enter the vent. What is the permeability of the second preform?