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In this paper, numerical simulations of lubricating grease flow in the grease pocket of a double restriction seal geometry using computational fluid dynamics are presented. The grease is treated as a singlephase Herschel-Bulkley fluid with different rheological properties corresponding to NLGI grade 00, 1 and 2. The numerical code and rheology model have been validated with a semi-analytical solution based on flow measurements using microparticle image velocimetry. The flow has been modelled for low and high rotational speeds driving the flow, and elevated temperatures. Also, the evolution of contaminant particles in the grease pocket is investigated. It was found that the flow and velocity distribution in the pocket-and consequently the contaminant particle concentration evolution, is characterized by the shear thinning rheology of the grease. With higher shear rates in the grease and higher temperatures, the grease approaches a more Newtonian type of behaviour leading to a reduced yield and shear thinning characteristics directly affecting the grease ability to transport contaminant particles.

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Compression moulding experiments of sheet moulding compound, visual observations of a vacuum test with prepregs and numerical models with two main approaches for computational fluid dynamics simulations of the mould filling phase are presented. One assumes that there are layers near the mould surfaces with much less viscosity and the other only use one viscosity model. The numerical experiments showed that the pressure could be accurately predicted with both approaches. The property necessary to predict correct pressure with altered mould closing velocities was that the bulk material had to obey shear-thinning effects. Preheating effects before compression were neglected, but altering the heating time until the prepreg was assumed to start flow had a significant effect. The experiments confirmed that the pressure is predominantly affected by the mould closing velocity. Regardless of the considered process settings, a first pressure top always appeared approximately at the logarithmic strain 0.25. A second top was associated with a slowdown of the press. The location of this was affected by the velocity and the vacuum, the latter indicating that vacuum assistance prevents a build-up of back pressure. Furthermore, heated prepreg above a critical temperature is observed to swell immediately as vacuum assistance is applied.