Browsing by Subject "OpenFOAM"

Now showing 1 - 5 of 5

A constructionist course for aerodynamic design and simulation analysis
(2020-12) Shelburne, William Daniel; Bisetti, Fabrizio
An undergraduate design-build-test course was created to offer students experience with a variety of modern engineering tools including CAD, additive manufacturing, wind tunnels, and computational fluid dynamics solvers. The course is organized so students may take an aerodynamic design from an idea to prototype testing with simulation data for comparison. This report focuses on the key lessons from the preparation of the course, so adequate direction may be given to provide students a path to success during a typical semester. An example consisting of the design of an airplane wing is used to demonstrate those problems and some solutions
An integrated peridynamics-finite volume based multi-phase flow, geomechanics and hydraulic fracture model
(2019-12-16) Agrawal, Shivam; Sharma, Mukul M.; Foster, John T., Ph. D.; Olson, Jon E; Mohanty, Kishore; Ouchi, Hisanao
Hydraulic fracturing in unconventional reservoirs exhibits several interesting phenomena including the interaction of hydraulic fractures with multi-scale heterogeneities such as natural fractures, stress/barrier layers, bedding planes, shale laminations, and mineralogy. Moreover, hydraulic fractures originating from different clusters or stages in a multi-stage, multi-cluster treatment interact among themselves. Mathematical models, with various degrees of numerical complexity, are developed for gaining better insights into the physics governing these phenomena. Peridynamics-based hydraulic fracturing model developed by Ouchi (2016) has been demonstrated to capture all of these phenomena. However, its major drawback is that it is computationally expensive. In this dissertation, we have extended the capabilities of the model to multi-phase flow and made it significantly faster by coupling it with the less expensive Finite Volume Method. The single-phase peridynamics flow model for slightly compressible, Newtonian fluids has been generalized for multiphase, multicomponent flow of compressible, non-Newtonian fluids. The generalized flow model has been coupled with the fracturing model and compared with laboratory experiments performed under low confining stresses. The extended model is also applied to simulate the growth of fractures from a new (child) well in the presence of depleted regions created by production from the fractures of an old (parent) well under high confining stresses. The interaction of a hydraulic fracture (HF) with a natural fracture (NF) is investigated. Remote shear failure of the NF due to the pororelastic stress changes caused by the propagating HF are considered. Consistent with the experiments, the remote shear failure is shown to result in the bending of the HF towards the NF before intersecting with it. Accounting for the effects of remote shear failure and poroelasticity, numerical crossing criteria for the HF-NF interaction are developed. The hydraulic fracturing model based on peridynamics (PD) theory is coupled with the less expensive Finite Volume Method (FVM), following the PD-FEM coupling method proposed by Galvanetto et al. (2016). Significant improvements in computational performance are achieved by the coupled model relative to the pure PD-based model, without compromising the unique original capabilities. By monitoring material damage in remote heterogeneous regions, a workflow for estimating the extent of the Stimulated Reservoir Volume (SRV) around a primary hydraulic fracture is developed. A sensitivity study for the effects of elastic properties of the formation, injection rate, and the reservoir fluid type on SRV extent is presented
Coupling Viscous Vorticity Equation (VISVE) method with OpenFOAM to predict turbulent flow around 2-D hydrofoils and cylinders
(2019-06-19) Yao, Hao; Kinnas, Spyros A.
The VIScous Vorticity Equation (VISVE) method has already been applied to solve the laminar flow around a cylinder and a hydrofoil at low Reynolds numbers. This method is more computationally efficient and spatially compact than a viscous flow method based on primitive variables. However, the VISVE method fails at high Reynolds numbers due to the effects of turbulence. In this thesis, a synchronous coupling method was developed to couple the VISVE and a turbulence model in OpenFOAM, enabling the VISVE method to solve the turbulent flow at high Reynolds numbers in a 2-D hydrofoil case and a 2-D cylinder case. The velocity, vorticity, and pressure calculated by the coupling method agree well with the results obtained by a RANS method.
Influence of Powder Distribution on Process Stability in Laser Beam Melting: Analysis of Melt Pool Dynamics by Numerical Simulations
(University of Texas at Austin, 2014) Gürtler, F.-J.; Karg, M.; Dobler, M.; Kohl, S.; Tzivilsky, I.; Schmidt, M.
The occurrence of defects in the additive manufacturing process of laser beam melting in metal powder bed can be reduced through empiric parameter optimization – but knowledge about basic effects like the influence of the composition of the powder layer on the melt pool is still limited. Particle size distribution and powder layer inhomogeneity after layer coating influence melt pool dynamics and may cause defects in the work pieces. This correlation can hardly be analyzed in experiments, so a three-dimensional transient numerical simulation model is used. The model is based on the continuity equation, the heat equation and the Navier-Stokes equation. Therefore, the finite-volume method capabilities in OpenFOAM are used. The free surfaces of the multi-phase system are calculated using the volume of fluid method. The powder beds have unimodal or bimodal distributions without random effects in the particle composition. Their density and thermal conductivity is adapted to reality. The investigations of the melt pool and the porosity formation demonstrate an advantage of more and smaller particles in the powder for compensation of defects in the powder bed, similar to the results of the experiments.
Large eddy simulation analysis of non-reacting sprays inside a high-g combustor
(2012-08) Martinez, Jaime, master of science in engineering; Raman, Venkat; Clemens, Noel T
Inter-turbine burners are useful devices for increasing engine power. To reduce the size of these combustion devices, ultra-compact combustor (UCC) concepts are necessary. One such UCC concept is the centrifugal-force based high-g combustor design. Here, a model ultra-compact combustor (UCC) with fuel spray injection is simulated using large eddy simulation (LES) and Reynolds-Averaged Navier-Stokes (RANS) methodologies to understand mixing and spray dispersion inside centrifugal-based combustion systems. Both non-evaporating and evaporating droplet simulations were carried, as well as the tracking of a passive scalar, to explore this multiphase system. Simulation results show that mixing of fuel and oxidizer is based on a jet-in-crossflow system, with the fuel jet issuing into a circulating oxidizer flow stream. It is seen that a a high velocity vortex-like ring develops in the inner core of the combustor, which has enough momentum to obstruct the path of combustion products. There is minimal fuel droplet and vapor segregation inside the combustor and enhanced turbulent mixing is seen at mid-radius.