Multiple-body simulation with emphasis on integrated Space Shuttle vehicle

The program to obtain intergrid communications - Pegasus - was enhanced to make better use of computing resources. Periodic block tridiagonal and penta-diagonal diagonal routines in OVERFLOW were modified to use a better algorithm to speed up the calculation for grids with periodic boundary conditions. Several programs were added to collar grid tools and a user friendly shell script was developed to help users generate collar grids. User interface for HYPGEN was modified to cope with the changes in HYPGEN. ET/SRB attach hardware grids were added to the computational model for the space shuttle and is currently incorporated into the refined shuttle model jointly developed at Johnson Space Center and Ames Research Center. Flow simulation for the integrated space shuttle vehicle at flight Reynolds number was carried out and compared with flight data as well as the earlier simulation for wind tunnel Reynolds number

Hypertension and Hypercholesterolemia: Biochemical and Pharmacological Studies in the Rabbit

1. Four groups of rabbits were set up to investigate the separate and combined effects of hypertension and hypercholesterolemia on a number of cardiovascular parameters, including in vivo vascular reactivity, phosphoinositide metabolism in aortic tissue, and platelet [Ca2+]i concentrations. The four groups were: a control group, a hypertensive group (perinephritis hypertension), a hypercholesterolemic group (0. 3% cholesterol diet), and a hypertensive-hypercholesterolemic group. 2. As the basic pharmacology of one of the agonists used in this work, endothelin, was poorly understood at the time these studies were planned, preliminary investigations into its effects in normotensive-normocholesterolemic animals were undertaken before embarking on the main project. In addition, some phosphoinositide studies were done using rat aorta. Endothelin-1 caused a dose-related increase in phosphoinositide hydrolysis in both rat and rabbit aorta. In rat aorta, endothelin-1-induced phosphoinositide hydrolysis increased with stimulation time for the first 30 minutes, and thereafter plateaued. The endothelin-stimulated effects were attenuated with endothelium removal, or with extracellular Ca2+ depletion. The endothelin-l-induced phosphoinositide hydrolysis was greater in rat aorta than in rabbit aorta. In vivo endothelin-1 caused a short-lived depressor response followed by a long-lasting pressor response in the rabbit. The pressor response was dose-related, and could be attenuated by the calcium antagonist nifedipine. 3. The imposition of perinephritis hypertension caused an increase of about 40 mmHg in mean arterial pressure in the operated rabbits, which stabilized after 6-7 weeks, while feeding a 0. 3% cholesterol diet induced a continual rise in plasma cholesterol levels in the rabbits, which reached 30 mmol/L after 4 months. In contrast to 0.3% cholesterol diet, perinephritis hypertension was a significant risk factor for cardiovascular deaths in the course of a 4-month study. There were significantly greater numbers of cardiovascular deaths in both the hypertensive and the hypertensive-hypercholesterolemic groups versus the control group (p= 0.038 and 0.009, respectively), but no significant difference between the hypercholesterolemic and the control group, or between the hypertensive-hypercholesterolemic and the hypertensive group. However, it is noteworthy that when the hypertensive-hypercholesterolemic group was compared to the hypertensive group, 0.3% cholesterol diet tended to augment the cardiovascular deaths in these hypertensive animals. 4. The imposition of perinephritis hypertension enhanced the pressor responses to angiotensin II, and endothelin-1, as well as the depressor responses to acetylcholine, isoproterenol, and nitroprusside at 2-3, 6-7, and 13-16 weeks of study. The differences tended to increase with the duration of hypertension for the pressor responses, but not for the depressor responses. The patterns of changes in the duration of hypertension differed from one pressor agonist to another, suggesting that structural changes in the vessel wall were not the sole explanation for enhanced vascular reactivity. Similar conclusions held for the depressor agonists. In contrast, the imposition of 0. 3% cholesterol diet had no effect on the in vivo vascular reactivity at any time point of the study, whether given to normotensive or hypertensive animals. 5. Neither perinephritis hypertension nor 0. 3% cholesterol diet caused any changes in the basal platelet [Ca2+] at the 17th week of study. 6. At the 18th week of study, perinephritis hypertension tended to enhance the noradrenaline-stimulated, but not the endothelin-stimulated phosphoinositide hydrolysis in rabbit aorta, but the difference was significant only at 10e-4 M noradrenaline for the hypertensive versus the control group. In contrast, 0.3% cholesterol feeding tended to decrease both noradrenaline- and endothelin-stimulated, phosphoinositide hydrolysis. The difference was significant at 10e-4 M noradrenaline for the hypercholesterolemic versus the control group, as well as for the hypertensive-hypercholesterolemic versus the hypertensive group, and at 10e-6 & 10e-5 M endothelin-1 for the hypertensive-hypercholesterolemic versus the hypertensive group. There was no difference in the basal [ 3H]-inositol phosphates formation between any experimental group and the control group, suggesting that neither perinephritis hypertension nor 0.3% cholesterol diet for 18 weeks altered the basal phosphoinositide metabolism in rabbit aorta. 7. Overall, in our study no significant additive effects of the two disease states were observed in any of the parameters examined. However, the number of biochemical responses, vessels and animals examined were limited, and further studies might identify sites of interaction between the two parameters

On computations of the integrated space shuttle flowfield using overset grids

Numerical simulations using the thin-layer Navier-Stokes equations and chimera (overset) grid approach were carried out for flows around the integrated space shuttle vehicle over a range of Mach numbers. Body-conforming grids were used for all the component grids. Testcases include a three-component overset grid--the external tank (ET), the solid rocket booster (SRB) and the orbiter (ORB), and a five-component overset grid--the ET, SRB, ORB, forward and aft attach hardware, configurations. The results were compared with the wind tunnel and flight data;In addition, a Poisson solution procedure (a special case of the vorticity-velocity formulation) using primitive variables was developed to solve three-dimensional, irrotational, inviscid flows for single as well as overset grids. The solutions were validated by comparisons with other analytical or numerical solutions, and/or experimental results for various geometries. The Poisson solution was also used as an initial guess for the thin-layer Navier-Stokes solution procedure to improve the efficiency of the numerical flow simulations. It was found that this approach resulted in roughly a 30% CPU time savings as compared with the procedure solving the thin-layer Navier-Stokes equations from a uniform free stream flowfield

Modeling of Permeability Reducing Vertical Conformance Treatments

Chemical treatments (usually polymer gels) are commonly used to improve the vertical conformance of oil reservoirs by selectively reducing the permeability in some zones near the well. The resuIts of such treatments have been sporadic and unpredictable. The objective of this study is to define those reservoir characteristics which lead to successful treatments and to provide guidelines for the application of conformance treatments by modeling them with a reservoir simulator-. The computer simulator is the BOAST model, a multiphase, three-. dimensional finite difference model written by Fanchi J. R. et al. and released by the Department of Energy. It was modified in areas such as the restart procedure , the rate allocation scheme, condition of well constraint, interpretation of relative permeability and implicit rate calculation to meet the objectives of this study. Several cases have been run to identify the reservoir properties that strongly influence the outcome of a conformance treatment. These are the vertical permeability, the permeability thickness product contrast between layers, the permeability contrast, and the level of permeability reduction near the injection well. The results presented interpret the test cases and provide a basis for possible implementation of a successful conformance treatment. Finality, a field case is presented in which actual reservoir properties were used to study a conformance treatment.Petroleum and Geosystems Engineerin

On automating domain connectivity for overset grids

An alternative method for domain connectivity among systems of overset grids is presented. Reference uniform Cartesian systems of points are used to achieve highly efficient domain connectivity, and form the basis for a future fully automated system. The Cartesian systems are used to approximated body surfaces and to map the computational space of component grids. By exploiting the characteristics of Cartesian Systems, Chimera type hole-cutting and identification of donor elements for intergrid boundary points can be carried out very efficiently. The method is tested for a range of geometrically complex multiple-body overset grid systems

User interface user's guide for HYPGEN

The user interface (UI) of HYPGEN is developed using Panel Library to shorten the learning curve for new users and provide easier ways to run HYPGEN for casual users as well as for advanced users. Menus, buttons, sliders, and type-in fields are used extensively in UI to allow users to point and click with a mouse to choose various available options or to change values of parameters. On-line help is provided to give users information on using UI without consulting the manual. Default values are set for most parameters and boundary conditions are determined by UI to further reduce the effort needed to run HYPGEN; however, users are free to make any changes and save it in a file for later use. A hook to PLOT3D is built in to allow graphics manipulation. The viewpoint and min/max box for PLOT3D windows are computed by UI and saved in a PLOT3D journal file. For large grids which take a long time to generate on workstations, the grid generator (HYPGEN) can be run on faster computers such as Crays, while UI stays at the workstation