PyFrac: A planar 3D hydraulic fracture simulator

Fluid driven fractures propagate in the upper earth crust either naturally or in response to engineered fluid injections. The quantitative prediction of their evolution is critical in order to better understand their dynamics as well as to optimize their creation. We present a Python implementation of an open-source hydraulic fracture propagation simulator based on the implicit level set algorithm originally developed by Peirce & Detournay (2008) -- "An implicit level set method for modeling hydraulically driven fractures". Comp. Meth. Appl. Mech. Engng, (33-40):2858--2885. This algorithm couples a finite discretization of the fracture with the use of the near tip asymptotic solutions of a steadily propagating semi-infinite hydraulic fracture. This allows to resolve the multi-scale processes governing hydraulic fracture growth accurately, even with relatively coarse meshes. We present an overview of the mathematical formulation, the numerical scheme and the details of our implementation. A series of problems including a radial hydraulic fracture verification benchmark, the propagation of a height contained hydraulic fracture, the lateral spreading of a magmatic dyke and the handling of fracture closure are presented to demonstrate the capabilities, accuracy and robustness of the implemented algorithm

OUTCOME OF INTRAVENOUS ACETAMINOPHEN IN PAIN RELIEF AMONG UNDERGOING ABDOMINAL HYSTERECTOMY

Objective; To determine the efficacy of intravenous acetaminophen for postoperative pain after abdominal hysterectomy. Material and Methods; A total of 114 women undergoing abdominal hysterectomy were taken in this study. The study was conducted from June 2018 to May 2019 at department of Anesthesiology, Nishtar Hospital, Multan. Results; Our study comprised of 114 ladies undergoing abdominal hysterectomy, mean age of the study cases was 54.13 ± 6.89 years (with minimum age of the patients was 39 years while maximum age was 68 years). Majority of our study cases i.e. 92 (80.7 %) had parity more than 3 and American Society of Anesthesiology (ASA) score level 1 in 93 (81.6%). Sixty one (53.1%) belonged to rural areas, while mean duration of surgery was 72.80 ± 11.32 minutes. Mean BMI level in our study cases was noted to be 23.98 ±4.17 Kg/m2 and obesity was present in 34 (29.8%) of our study cases and Efficacy in terms of pain reduction was 73.7%. Conclusion; Our study results support the use of intravenous acetaminophen (IVA) for pain management in patients undergoing abdominal hysterectomy. Intravenous acetaminophen is safe, reliable and effective for the pain management in postoperative abdominal hysterectomy patients which was associated with shorter hospital stay and cost effective for the suffering families. No adverse reactions were noted in this study with the use of intravenous acetaminophen. Keywords; Intravenous acetaminophen, pain relief, Abdominal Hysterectomy. DOI: 10.7176/JMPB/62-10 Publication date: December 31st 201

Explicit versus implicit front advancing schemes for the simulation of hydraulic fracture growth

The proper computation of the time evolution of the fracture front is the main challenge of three-dimensional (3D) hydraulic fracture growth simulation. We discuss explicit and implicit variants of a hydraulic fracture propagation scheme based on a level set representation of the fracture. Such a scheme couples a finite discretization of the governing equations and the near-tip hydraulic fracture asymptotes. We benchmark the accuracy, robustness, and stability of these different front advancing schemes on a number of test cases. Our results indicate a large computational gain of the explicit scheme at the expense of a slightly less accurate solution (few percent less accuracy over few time steps) when crossing heterogeneities. The predictor corrector scheme combines at least an approximately 25% computational gain while retaining the stability and accuracy of the fully implicit version of the scheme in all cases

Laminar - turbulent transition in the propagation of height contained hydraulic fracture

High injection rate hydraulic fracturing can have Reynolds number as high as 10000. For such high Reynolds numbers, turbulent flow is likely to occur. In this paper, we investigate the effect of turbulence on the propagation of hight contained hydraulic fractures, commonly referred to as PKN fractures. We discuss different scalings for the fracture width, length and pressure under limiting laminar, turbulent smooth and turbulent rough flow regimes. We implement an explicit, central numerical scheme to solve the continuity and friction factor based momentum conservation equations, taking into account the full variation of friction factor with Reynolds number and relative fracture roughness. The scheme is validated against the analytical solution of the PKN model. The results show that the local Reynolds number evolves from a maximum value at the inlet to zero at the tip, with a transition from turbulent to laminar at some point along the fracture length, depending on the value of inlet Reynolds number. Results showing the effect of smooth and rough turbulence on the fracture length and fracture width depending on the Reynolds number are finally presented

ASSOCIATION OF VARICEAL BLEED WITH SEVERITY OF LIVER CIRRHOSIS AT A TERTIARY CARE HOSPITAL

Background; A major cause of cirrhosis-related morbidity and mortality is the development of variceal bleeding, a direct consequence of portal hypertension. Each episode of active variceal bleeding is associated with 30 percent mortality. This study was planned to determine frequency of variceal bleeding in patients with liver cirrhosis and frequency of in-hospital mortality of these patients in our population. Objective; To determine the frequency of variceal bleed in hospitalized patients with cirrhosis of liver and its outcome in terms of in-hospital mortality. Material and Methods; Consecutive 139 Patient diagnosed with cirrhosis of liver were included in this cross-sectional study from department of Medicine, Bahawal Victoria hospital Bahawalpur. Complete history and physical examination was assessed to document duration of duration of liver disease, ascites, Hepatic encephalopathy, Previous GI bleed and systemic coagulopathy. All the patients had undergone diagnostic upper GI endoscopic examination to document varices. Results; Of these 139 study cases, 77 (55.4 %) were male and 62 (44.6 %) were female. Mean age of our study cases was 45.50 ± 10.81 years. Mean duration of disease (liver cirrhosis) was 3.25 ± 2.32 years. Majority of our study cases i.e. 94 (67.6%) were having liver cirrhosis for the duration of less than 5 years. Child-Pugh class C was more prevalent i.e. 77 (55.4%) of our study cases. Variceal bleeding was observed in 100 (71.9 %) of our study cases. Frequency of mortality was 35 (25.2%) in our study cases with liver cirrhosis, while frequency of mortality in patients with variceal bleeding was seen in 31 (31%). Variceal bleeding was significantly associated with disease severity (p<0.001). Conclusion; Very high frequency of variceal bleeding was observed in patients with liver cirrhosis. In-hospital mortality was significantly more prevalent in patients with variceal bleeding than without bleed. Variceal bleeding was significantly more seen in patients with increasing age, duration of disease and with more severe level of disease (Child Pugh class C). There was no statistically significant difference of bleeding with regards to gender. Keywords; Liver Cirrhosis, Variceal bleeding, Mortality. DOI: 10.7176/JMPB/62-13 Publication date: December 31st 201

Energy efficient parallel configuration based six degree of freedom machining bed

The process of material removal from a workpiece to obtain the desired shape is termed machining. Present-day material removal technologies have high spindle speeds and thus allow quick material removal. These high-speed spindles are highly exposed to vibrations and, as a result, the accuracy of the final workpiece’s dimensions is compromised. To overcome this problem, the motion of the tool is restricted, and multiple degrees of freedom are given through the motion of the workpiece in different axes. A machining bed configured as a parallel manipulator capable of giving six degrees of freedom (DOF) to the workpiece is proposed in this regard. However, the proposed six DOF machining bed should be energy efficient to avoid an increase in machining cost. The benefit of using the proposed configuration is a reduction in dimensional error and computational time which, as a result, reduces the energy utilization, vibrations, and machining time in practice. This paper presents kinematics, dynamics and energy efficiency models, and the development of the proposed configuration of the machining bed. The energy efficiency model is derived from the dynamics model. The models are verified in simulation and experimentally. To minimize error and computation time, a PID controller is also designed and tested in simulation as well as experimentally. The resulting energy efficiency is also analyzed. The results verify the efficacy of the proposed configuration of the machining bed, minimizing position error to 2% and reducing computation time by 27%, hence reducing the energy consumption and enhancing the energy efficiency by 60%