A Library Based Approach for Rigid Body Dynamics Simulation

Koomullil, Roy P.; Prewitt, Nathan C.

doi:10.2514/6.2007-4476

Cited by 9 publications

(1 citation statement)

References 17 publications

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“…The discretized form of the governing equations are solved in a parallel framework using MPI [12] for inter processor communication and METIS [21] to decompose the domain into multiple regions. More details on the numerical approach and validation are reported in [26][28][27][25][23][24][22][10]. …”

Section: Numerical Approachesmentioning

confidence: 99%

Assessment of surgical effects on patients with obstructive sleep apnea syndrome using computational fluid dynamics simulations

Cheng

Koomullil

Ito

et al. 2014

Mathematics and Computers in Simulation

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Obstructive sleep apnea syndrome is one of the most common sleep disorders. To treat patients with this health problem, it is important to detect the severity of this syndrome and occlusion sites in each patient. The goal of this study is to test the hypothesis that the cure of obstructive sleep apnea syndrome by maxillomandibular advancement surgery can be predicted by analyzing the effect of anatomical airway changes on the pressure effort required for normal breathing using a high-fidelity, 3-D numerical model. The employed numerical model consists of: 1) 3-D upper airway geometry construction from patient-specific computed tomographic scans using an image segmentation technique, 2) mixed-element mesh generation of the numerically constructed airway geometry for discretizing the domain of interest, and 3) computational fluid dynamics simulations for predicting the flow field within the airway and the degree of severity of breathing obstruction. In the present study, both laminar and turbulent flow simulations were performed to predict the flow field in the upper airway of the selected patients before and after maxillomandibular advancement surgery. Patients of different body mass indices were also studied to assess their effects. The numerical results were analyzed to evaluate the pressure gradient along the upper airway. The magnitude of the pressure gradient is regarded as the pressure effort required for breathing, and the extent of reduction of the pressure effort is taken to measure the success of the surgery. The description of the employed numerical model, numerical results from simulations of various patients, and suggestion for future work are detailed in this paper.

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Section: Numerical Approachesmentioning

confidence: 99%

Assessment of surgical effects on patients with obstructive sleep apnea syndrome using computational fluid dynamics simulations

Cheng

Koomullil

Ito

et al. 2014

Mathematics and Computers in Simulation

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The Effect of Roll Rate on Simulated Entry Vehicle Ballistic Range Tests

Ernst

Hickey

Robertson

et al. 2023

Journal of Spacecraft and Rockets

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Free-flight computational fluid/rigid-body dynamics simulations are now being explored as a way to augment physical experiments for characterizing the dynamic behavior of blunt-body atmospheric entry vehicles. Initializing these simulations with accurate initial conditions is critical to achieving validation against experimental results and characterizing vehicle behavior. This paper explores the impact of a nonnegligible initial roll rate on numerical free-flight simulations of ballistic range tests using the FUN3D Navier–Stokes flow solver and POST2 trajectory propagator. These ballistic range shots were performed on a model of the Supersonic Inflatable Aerodynamic Decelerator at the NASA Ames Hypervelocity Free-Flight Aerodynamics Facility. In the absence of measured roll data, a method for reconstructing the initial roll rate is developed assuming that a nonnegligible roll rate accounts for the exchange in amplitude between the experimental pitch and yaw data. Simulations of three shots spanning a range of initial roll rates are executed to evaluate the new method. Results are validated against the physical ballistic range tests. Simulations with the reconstructed roll rate are more accurate to the experimental data than those assuming a negligible initial roll rate. Direct calculation of the pitch damping coefficient also captures the effect of roll rate on pitching moment.

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