This work explores a route to unify Reynolds averaged (RANS) and large eddy simulation (LES). The... more This work explores a route to unify Reynolds averaged (RANS) and large eddy simulation (LES). The approach is to use a slightly modified Reynolds stress transport model for any mesh resolution. The model is formulated in terms of both total kinetic energy and modeled kinetic energy in such a way that the RST model correctly reproduces RANS results, LES results, and even DNS results (by turning itself off). The model equations do not contain functions of the mesh size within any of the model terms or constants. It is demonstrated that this approach works at any mesh resolution. In addition, the model naturally transitions between mesh resolutions, either coarse to fine or vice-versa. It is shown that for LES mesh resolutions the model returns a turbulent length scale that is proportional to the mesh size (the classic LES turbulent length scale).
APS Division of Fluid Dynamics Meeting Abstracts, Nov 1, 2002
The modeling of rotating turbulence has been attempted using the turbulent body force potentials.... more The modeling of rotating turbulence has been attempted using the turbulent body force potentials. Particular care has been taken to see that the model gives the same results regardless of the frame with respect to which the model is being computed. Frame invariant flow-dependent quantities are used for all the terms. The model is integrable upto the wall, and extra
The open port interface (OPI) coupled to an atmospheric pressure ion source is used to capture, d... more The open port interface (OPI) coupled to an atmospheric pressure ion source is used to capture, dilute, focus, and transport nanoliter volume sample droplets for high-speed mass spectrometric analysis. For typical applications, the system has been optimized to achieve 1 Hz nanoliter volume sample transfer rates while simultaneously diluting the sample >1000-fold to minimize sample matrix-induced ionization suppression. Geometric, flow, and dispensing alterations to the system presented here demonstrate that sample transfer rates for the OPI of at least 15 Hz are possible. The fluid dynamic processes that enable sampling rates of 1 Hz and greater are examined in detail by correlating computational fluid dynamics simulations, analytic calculations, experimental data, photographic footage, and reference to the fluid dynamics literature. The resulting models and experimental results provide the rationale underlying the design and tuning of the system as well as information for developing optimized analytical methods. In combination with acoustic droplet dispensing, referred to as acoustic ejection mass spectrometry (AEMS), this system can be considered to be a special case of flow injection analysis with unique features that control the peak width, symmetry, and segregation of the samples transported in a fluid while simultaneously enabling their mixing and dilution with carrier fluids. In addition, conditions are established to prevent direct contact of the sample with a surface enabling, in combination with a contact-free dispenser like acoustic ejection, a dramatic reduction in sample-to-sample carry-over.
This work explores a route to unify Reynolds averaged (RANS) and large eddy simulation (LES). The... more This work explores a route to unify Reynolds averaged (RANS) and large eddy simulation (LES). The approach is to use a slightly modified Reynolds stress transport model for any mesh resolution. The model is formulated in terms of both total kinetic energy and modeled kinetic energy in such a way that the RST model correctly reproduces RANS results, LES results, and even DNS results (by turning itself off). The model equations do not contain functions of the mesh size within any of the model terms or constants. It is demonstrated that this approach works at any mesh resolution. In addition, the model naturally transitions between mesh resolutions, either coarse to fine or vice-versa. It is shown that for LES mesh resolutions the model returns a turbulent length scale that is proportional to the mesh size (the classic LES turbulent length scale).
APS Division of Fluid Dynamics Meeting Abstracts, Nov 1, 2002
The modeling of rotating turbulence has been attempted using the turbulent body force potentials.... more The modeling of rotating turbulence has been attempted using the turbulent body force potentials. Particular care has been taken to see that the model gives the same results regardless of the frame with respect to which the model is being computed. Frame invariant flow-dependent quantities are used for all the terms. The model is integrable upto the wall, and extra
The open port interface (OPI) coupled to an atmospheric pressure ion source is used to capture, d... more The open port interface (OPI) coupled to an atmospheric pressure ion source is used to capture, dilute, focus, and transport nanoliter volume sample droplets for high-speed mass spectrometric analysis. For typical applications, the system has been optimized to achieve 1 Hz nanoliter volume sample transfer rates while simultaneously diluting the sample >1000-fold to minimize sample matrix-induced ionization suppression. Geometric, flow, and dispensing alterations to the system presented here demonstrate that sample transfer rates for the OPI of at least 15 Hz are possible. The fluid dynamic processes that enable sampling rates of 1 Hz and greater are examined in detail by correlating computational fluid dynamics simulations, analytic calculations, experimental data, photographic footage, and reference to the fluid dynamics literature. The resulting models and experimental results provide the rationale underlying the design and tuning of the system as well as information for developing optimized analytical methods. In combination with acoustic droplet dispensing, referred to as acoustic ejection mass spectrometry (AEMS), this system can be considered to be a special case of flow injection analysis with unique features that control the peak width, symmetry, and segregation of the samples transported in a fluid while simultaneously enabling their mixing and dilution with carrier fluids. In addition, conditions are established to prevent direct contact of the sample with a surface enabling, in combination with a contact-free dispenser like acoustic ejection, a dramatic reduction in sample-to-sample carry-over.
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