Forming the air-core, is the one of flow properties in hydrocyclone. The swirling flow causes a cylindrical low pressure area at the axis of hydrocyclone which is constant throughout the entire length of the hydrocyclone. Air-core affects the separation efficiency. In this study, low pressure areas were used to predict air-core diameter. Computational fluid dynamics ((CFD)) method was used to determine the pressure distribution inside of hydrocyclone. Three models including: the renormalization group k-e model, the Reynolds stress model, and the large-eddy simulation model, were compared for the prediction of aircore dimension. Air-core diameter was evaluated by using three planes, one on cylindrical part and two on conical section. Results show that, the RSM turbulence model is more accurate than two other models.

Blood is one of the vital fluids of the human body. Measurement of its viscosity and other properties is very important in detecting and understanding different cardiovascular diseases. In this study, the blood flow in a concentric cylinder viscometer was simulated numerically. The blood flow patterns were analyzed by applying different rotational speed of inner cylinder. Creation of a Couette flow, end effects and suitable rotational speed limit were analyzed. The amount of the torque applied to the inner cylinder which prevents the generation of the Taylor vortices was also predicted. From the obtained results, one can conclude that these vortices were not as important as the end effects were. In order to keep the blood sample temperature within a constant and acceptable range a thermal bath was used. Heat removal rate with different inflow rates of coolant was also predicted numerically.

Efficiency of domestic ventilation waste heat recovery systems (WHRS) depends not only on the amount of waste heat recovered, but also on the energy involved in running fans to drive air through the system. Computational fluid dynamics ((CFD)) can be a powerful tool for analysing WHRS losses (thus predicting fan energy usage), but the Computational effort involved can limit the value of (CFD) as a practical design tool. This study presents a range of assumptions and simplifications that can be applied to reduce the Computational effort associated with the (CFD) analysis of a WHRS. The importance of experimental validation to assess the effect of errors introduced by the simplifying assumptions is discussed. In an example case, application of the methods presented have allowed total pressure losses (excluding the fixed losses through the heat exchanger) to be reduced by over 50% in comparison with an initial prototype design, with proportional reduction in fan energy usage. This highlights the value of sufficiently simplified (CFD) analyses within a typical WHRS product development cycle.

Combining two methods of Computational fluid dynamics ((CFD)) and design of experiments (DOE) was proposed in modeling to simultaneously benefit from the advantages of both modeling methods. The presented method was validated using a coal hydraulic classifier in an industrial scale. The effects of operating parameters, including feed flow rate, solid content and baffle length, were evaluated based on the classifier overflow velocity and cut-size as the process responses. The evaluation sequence was as follows: the variation levels of parameters was first evaluated using industrial measurement, and then a suitable experimental design was carried out and the DOE matrix was translated to (CFD) input. Afterwards, the overflow velocity values were predicted by (CFD), and the cut-size values were determined using industrial and (CFD) results. The overflow velocity and cut-size values were statistically analyzed to develop the prediction models for DOE responses; and finally, the main interaction effects were interpreted with respect to DOE and (CFD) results. Statistical effect plots along with (CFD) fluid flow patterns showed the effects of type and magnitude of operating parameters on the classifier performance, and visualized the mechanism by which those effects occurred. The suggested modeling method seems to be a useful approach for better understanding the real operational phenomena within the fluid-base separation devices. Furthermore, the individual interaction effects can also be identified and used for interpretation of responses in nonlinear processes.

Membrane bioreactor (MBR) is an effective technology for wastewater treatment and water reuse which is becoming increasingly popular due to its numerous applications and advantages over conventional activated sludge process. This novel technology have advantages of small footprint, high concentration of mixed liquor suspended solids (MLSS), high removal efficiency of chemical oxygen demand (COD), less production of excess sludge and to be reliable and simple to operate. Membrane fouling and its consequences, regarding plant maintenance and operating costs, has gained attention in recent years as a major obstacle for development of this technology. Various methods have been used to reduce membrane fouling and new solutions are frequently proposed and used.