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Computational modeling is an effective and inexpensive way to study the operational characteristics of several systems. The goal of the current project is to develop a numerical model that predicts the performance of an oilfield shale shaker. A computer controlled shaker operation enables the drilling engineer and shaker operator to have prior knowledge of performance when certain operational parameters are changed. The current model is an attempt to determine the effect of various operating parameter on shaker performance (capacity). A yield stress model that describes flow of drilling fluid (mud) on a shale shaker was developed using continuum equations of cake filtration and validated using full scale experiments on M-I SWACO's Mongoose PT shaker machine and pilot scale experiments on a packed bed in the laboratory. The experiments also served to fill in gaps in the model by providing input data such as particle velocities and cake porosities. The model shows similar trends and an acceptable match with experimental data. The results also show the variation of shaker capacity with each operational parameter. This work is considered to be the first attempt to incorporate the yield stress property of drilling mud in a numerical model in terms of the friction factor.

Chronic venous stasis is a disease condition resulting from valvular incompetence caused by either thrombophlebitis or congenital valvular abnormalities. This is a major concern today affecting as many as twenty four million people. While it is usually managed by nonoperative methods, the severity of the disease in some cases demands the exploration of other means of treating this condition. Hence, replacement of damaged venous valves by prosthetic ones is an option that is being pursued. If successful, a prosthetic valve would help to restore the function of the damaged native venous valves. The goal of the current project was to validate the design of a venous valve previously designed (US Patent Application # 11/ 282,515) using a Computational Fluid Dynamics (CFD) simulation. This simulation would help determine parameters which could not be obtained by in-vitro flow modeling and quantify the fluid-solid interactions at a higher resolution than is possible experimentally. Several fluid dynamics parameters were obtained under both steady state (forward and reverse directions) and pulsatile conditions at mean velocities of 0.05 and 0.1 m/s. These approximated conditions seen under resting supine and walking conditions. Parameters obtained were the pressure distribution, velocity profiles, and shear stresses around the valve, and the residence time of the fluid within the valve and behind the leaflets. The velocity profiles gave an insight into the flow patterns within and around the valve and parameters such as the opening and closing torques, accelerations, and impact forces acting to open and close the leaflets as well as the valve resistances were calculated from the pressures. Analysis of the results revealed that the shear stresses are not likely to cause hemolysis. The highest residence times were observed in the sheltered regions just behind the leaflets in all cases but especially for the forward flow condition with average inlet velocity of 0.05 m/s, indicating the potential for thrombus formation in those areas.