Highlights37 year-old morbidly obese female status post MGB presented with edema after 8 months.Severe malnutrition and hypocupremia progressed to pancytopenia and liver failure.No improvements after corrective surgery, death 13 months after primary surgery.Careful post-op care is crucial especially with baseline liver disease.

Stirred bioreactors are commonly used unit operations in the pharmaceutical industry. In this study, computational fluid dynamics (CFD) was used in order to analyze the influence of the impeller configuration (Segment–Segment and Segment–Rushton impeller configurations) and the impeller rotational speed (an operational parameter) on the hydrodynamic behaviour and mixing performance of a bioreactor equipped with a double impeller. A relatively close agreement between the power values obtained from the CFD model and those measured experimentally was observed. Various parameters such as velocity profiles, stress generated by impellers due to the turbulence and velocity gradient, flow number, and mixing time were used to compare the CFD simulations. It was observed that the impeller’s RPM could change the intensity of the interaction between the impellers when a Segment–Rushton impeller was used. In general, increasing the RPM led to an increase in total power and the stress acting on the cells and to a shorter mixing time. At a constant RPM, the Segment–Rushton impeller configuration had higher total power and stress acting on cells compared to the Segment–Segment impeller configuration. At lower RPM values (i.e., 50 and 100), the Segment–Segment impeller provided a shorter mixing time. Conversely, at the highest RPM (i.e., 150) the Segment–Rushton impeller had a shorter mixing time compared to the Segment–Segment impeller; this was attributed to the high level of turbulence generated with the former impeller configuration at high RPM.

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A study is presented to evaluate the capabilities of the standard k-turbulence model and the k-turbulence model with added source terms in predicting the experimentally measured turbulence modulation due to the presence of particles in horizontal pneumatic conveying, in the context of a CFD-DEM Eulerian-Langrangian simulation. Experiments were performed using a 6.5 m long, 0.075 m diameter horizontal pipe in conjunction with a laser Doppler anemometry (LDA) system. Spherical glass beads with two different sizes, 1.5 mm and 2 mm, were used. Simulations were carried out using the commercial Discrete Element Method (DEM) software EDEM, coupled with the Computational Fluid Dynamics (CFD) package FLUENT. Hybrid source terms were added to the conventional k- turbulence model to take into account the influence of the dispersed phase on the carrier phase turbulence intensity. The simulation results showed that the turbulence modulation depends strongly on the model parameter Cɛ3. Both the standard k- turbulence model and the k- turbulence model with the hybrid source terms could predict the gas phase turbulence intensity trend only generally, with in all cases a noticeable discrepancy between simulation and experimental results was observed, particularly for the regions close to the pipe wall. It was also observed that in some cases the addition of the source terms to the k- turbulence model did not improve the simulation results when compared to the simulation results of the standard k- turbulence model, though in the lower part of the pipe where particle loading was greater due to gravitational effects the model with added source terms performed somewhat better.