  Long fiber composite materials can be elaborated by Liquid Composite Molding
(LCM), a family of processes where fibrous preforms are injected by a low
viscosity resin. During this process, we have to pay particular attention to
the void formation inside the preform because it could modify the material
final characteristics. Indeed, a preform presents two different porosity
scales: between yarns called macropores and inside yarns, namely micropores.
