Computational Fluid Mixing

The physical characterisation of a microscale parallel bioreactor platform with an industrial CHO cell line expressing an IgG4

“…On the other hand, the volume integral of the dissipation rates yields a power number that is only 55% of the experimentally measured value. However, that is consistent with reported under-predictions based on the k- approach [24] which are usually attributed to the strong streamline curvature found in stirred vessel flows, along with the strong anisotropy of the turbulence close to the impeller blades [30].…”

“…Previous studies (e.g. Rielly & Gimbun, [24]) indicate that k- turbulence models give reasonable predictions of the mean velocity fields and impeller torques. On the other hand, the volume integral of the dissipation rates yields a power number that is only 55% of the experimentally measured value.…”

Linking power and flow in rotor-stator mixers

“…This method is more reliable and accurate than taking the volume integral of , since all RANS turbulence models inherently under-predict turbulent dissipation (Rielly and Gimbun, 2009). All solid boundaries were given the no-slip condition whilst the shear stress at the free surface was specified as 0 in all directions.…”

The effect of axial impeller geometry on the link between power and flow numbers

“…It is widely believed that the sliding mesh (SM) method, in which the relative movement between the blades and the baffles is captured in a time dependent simulation, is more accurate than the MRF method but also much more expensive. 49,50 It has been found by a number of authors that for relatively low D=T ratios, such as those used in this study, that the interaction between the blades and the baffles is fairly weak and so the MRF technique produces similar results to the SM technique. [46][47][48][51][52][53] Therefore, considering its significantly reduced cost, and that this study benefits from covering a wide range of geometries, the MRF method would seem a suitable choice.…”

“…40 The no-slip boundary condition was applied to all solid boundaries, and the liquid-air interface at the top of the vessel was modeled with a zero-shear stress boundary condition, as is typical with simulations of stirred vessels. 49 Since the geometry exhibits planes of symmetry, periodic boundaries were used to reduce the computational expense; one quarter of the total geometry was simulated. The multiple reference frame (MRF) method was used to model the rotation of the impeller.…”