A non-uniform pressure is assumed inside the volume. The gas flow in FVMBAG1 is solved using a finite volume integration scheme which allows the gas flow through the airbag to be correctly modeled.

Since the gas flow simulated, the unfolding and deployments behavior is correct which is needed for out of position occupant simulations and curtain airbag deployments.

Perfect gas law and adiabatic conditions are assumed. Injected mass, velocity and temperature are defined as a time function. The injected velocity is obtained using:(1)
v in ( t )= dm( t ) dt S ρ in ( t ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWG2bWaaS baaSqaaiaadMgacaWGUbaabeaakmaabmaabaGaamiDaaGaayjkaiaa wMcaaiabg2da9maalaaabaWaaSGaaeaacaWGKbGaamyBamaabmaaba GaamiDaaGaayjkaiaawMcaaaqaaiaadsgacaWG0baaaaqaaiaadofa cqaHbpGCdaWgaaWcbaGaamyAaiaad6gaaeqaaOWaaeWaaeaacaWG0b aacaGLOaGaayzkaaaaaaaa@4A8B@

Where, S is the injector surface.

A sensor may define the inflator starting time.

Deflation of vent hole is available after reaching a pressure (Pdef) or time (tdef) criteria.

In this version, heat gas capacity Cp is assumed constant.

More further detail, refer to FVMBAG1 Airbag Modeling Guidelines.