This paper discusses results from two dimensional simulations of a "smooth" Eppler 398 ... more This paper discusses results from two dimensional simulations of a "smooth" Eppler 398 wing profile and an inflatable or "bumpy" Eppler 398 wing profile. A discussion on computed flowfields follows for a number of test cases in an eort to understand the unique behavior seen in wind tunnel tests of inflatable wings. Numerical and experimental observations suggest that the flow
This paper discusses results from two dimensional simulations of a "smooth" Eppler 398 ... more This paper discusses results from two dimensional simulations of a "smooth" Eppler 398 wing profile and an inflatable or "bumpy" Eppler 398 wing profile. A discussion on computed flowfields follows for a number of test cases in an eort to understand the unique behavior seen in wind tunnel tests of inflatable wings. Numerical and experimental observations suggest that the flow
45th AIAA Aerospace Sciences Meeting and Exhibit, 2007
By its nature, the cache optimization of a computational fluid dynamics (CFD) code is most readil... more By its nature, the cache optimization of a computational fluid dynamics (CFD) code is most readily assessed on relatively simple geometries and on problems that only require the core routines. Having previously conducted cache optimization on two in-house codes at the ...
44th AIAA Aerospace Sciences Meeting and Exhibit, 2006
This paper presents an analysis of performance improvement of two CFD codes, the structured two-d... more This paper presents an analysis of performance improvement of two CFD codes, the structured two-dimensional code GHOST and the unstructured two-/three-dimensional code UNCLE, both in-house codes at the University of Kentucky, with the specific target of cache ...
... This process is 1Graduate Student, Dept. of Mechanical Engineering, [email protected], Student... more ... This process is 1Graduate Student, Dept. of Mechanical Engineering, [email protected], Student Member AIAA. ... KFC2 consists of commodity nodes each with a 2000+XP AMD Athlon processor and 256 MB RAM. The network is four-way channel bonded Fast Ethernet. ...
... Some Consequences of the Collision of a Comet and Jupiter Zahnle (NASAJARC), M.-M. Mac Low (U... more ... Some Consequences of the Collision of a Comet and Jupiter Zahnle (NASAJARC), M.-M. Mac Low (U. Chicago), CF Chyba (NASA/GSFC) At the time we write this, comet Shoemaker-Levy IX (1993e) is expected to strike Jupiter on July 21 1994 (IAU circular 5800; D. K Yeomans ...
Since its introduction in 1997, the Detached Eddy Simulation (DES) turbulence model has been used... more Since its introduction in 1997, the Detached Eddy Simulation (DES) turbulence model has been used successfully to simulate turbulence in an increasing number of computational fluid dynamics applications, primarily in aerospace engineering. The characteristics of DES - its compatibility with eddy viscosity models and its ability to smoothly transit from a Reynolds-Averaged Navier-Stokes (RANS) to a Large Eddy Simulation (LES) turbulence model - make it attractive as a potential turbulence model for atmospheric simulation. The current implementation of the model within the EPIC GCM is designed to provide turbulence closure from the planetary boundary layer to the upper atmosphere. We will present validation studies based on well-studied engineering and geophysical benchmark flows to examine the effects of DES model type (the Spalart-Allmaras or Menter SST version), boundary condition construction, coriolis forces, and problem scale. These validation tests are used to correct and calibrate the model, an iterative process that provides a more quantitative check of the DES techniques. Our main goal is to constrain a versatile planetary boundary-layer formulation using the full spectrum of available engineering data such that it provides good accuracy for a wide range of planetary applications, including Venus, Earth, Mars, Titan, and Triton. This work is sponsored by the NASA EPSCoR and Planetary Atmospheres Programs and the Kentucky Space Grant Consortium.
The use of actuators has been seen as an effective means for controlling flow over plates, airfoi... more The use of actuators has been seen as an effective means for controlling flow over plates, airfoils, and turbine blades. The use of plasma actuators is attractive since it lacks moving parts and can be easily integrated onto different geometries. There have been many experiments dealing with boundary layer control using passive elements, such as tripping the flow with surface roughness or other means of perturbing the surface without the addition of an external source of energy. There have also been many different active methods for controlling the boundary layer; examples include the use of piezoelectric actuators and morphing surfaces. Unlike many of the active methods listed above, plasma actuators are attractive because they can be easily implemented on a number of different geometries. Plasma Actuators have been proved, experimentally and numerically, as a potentially effective method for boundary layer control. This boundary layer control is driven by a body force vector tangent to the surface where the actuator is integrated. The purpose of this paper is to introduce the mathematical models used to describe the phenomena associated with plasma actuators, to implement them in a three-dimensional unstructured grid code, and to verify it by comparing numerical and experimental results.
43rd AIAA Aerospace Sciences Meeting and Exhibit, 2005
A cell-centered pressure based method is presented in this paper, and it is implemented in a new ... more A cell-centered pressure based method is presented in this paper, and it is implemented in a new two/three-dimensional parallel unstructured CFD code to meet the challenges of physical problems with complex geometries and complicated boundary conditions while maintaining high computational efficiency. The method uses a second order upwind scheme in space and a second order backward scheme for time accuracy. The SIMPLE algorithm in conjunction with the Rhie and Chow approach solves the continuity equation, minimizing undesirable pressure oscillations. The code is parallelized using METIS domain decomposition with good load balancing across computational nodes. In order to demonstrate the accuracy and performance of the current cell-centered pressure based method, several test cases are presented for validation such as two-dimensional incompressible flow past a flat plate, two/three-dimensional driven cavity flow, and two/three-dimensional flow over a circular cylinder. Notably, an extensive qualitative and quantitative study of two-dimensional flow over a circular cylinder for low Reynolds pressure-based method, several test cases are presented for validation such as two-dimensional incompressible flow past a flat plate, two/three-dimensional driven cavity flow, and two/three-dimensional flow over a circular cylinder.
The aerospace community is on the verge of a new generation of practical active flow control devi... more The aerospace community is on the verge of a new generation of practical active flow control devices from synthetic jets to plasma actuators. However, even as the mechanical challenges of implementing these systems seem attainable, the proper placement, orientation, and energy inputs to achieve the maximum benefit in a variety of flow conditions are unknown. Successful application of computational fluid dynamics (CFD) to this kind of control problem critically depends on an efficient searching algorithm for design optimization. Based on our previous research of single suction/blowing jet control on a NACA 0012 airfoil, the design parameters of a test multi-jet system are proposed. The convergence rates of a real-coded "Explicit Adaptive Range Normal Distribution" (EARND) genetic algorithm (GA) without/with Diversity Control are compared. The GA drives numerous CFD simulations, guiding the configuration of a suction jet and a blowing jet on the airfoil's upper surface. Reasonable optimum control values are determined within the control parameter range, suggesting the potential use of Evolutionary Algorithms to optimize these types of flow control applications.
A cell-centered pressure based method is presented in this paper, and it is implemented in a new ... more A cell-centered pressure based method is presented in this paper, and it is implemented in a new two/three-dimensional parallel unstructured CFD code to meet the challenges of physical problems with complex geometries and complicated boundary conditions while maintaining high computational efficiency. The method uses a second order upwind scheme in space and a second order backward scheme for time accuracy. The SIMPLE algorithm in conjunction with the Rhie and Chow approach solves the continuity equation, minimizing undesirable pressure oscillations. The code is parallelized using METIS domain decomposition with good load balancing across computational nodes. In order to demonstrate the accuracy and performance of the current cell-centered pressure based method, several test cases are presented for validation such as two-dimensional incompressible flow past a flat plate, two/three-dimensional driven cavity flow, and two/three-dimensional flow over a circular cylinder. Notably, an extensive qualitative and quantitative study of two-dimensional flow over a circular cylinder for low Reynolds pressure-based method, several test cases are presented for validation such as two-dimensional incompressible flow past a flat plate, two/three-dimensional driven cavity flow, and two/three-dimensional flow over a circular cylinder.
This paper discusses results from two dimensional simulations of a "smooth" Eppler 398 ... more This paper discusses results from two dimensional simulations of a "smooth" Eppler 398 wing profile and an inflatable or "bumpy" Eppler 398 wing profile. A discussion on computed flowfields follows for a number of test cases in an eort to understand the unique behavior seen in wind tunnel tests of inflatable wings. Numerical and experimental observations suggest that the flow
This paper discusses results from two dimensional simulations of a "smooth" Eppler 398 ... more This paper discusses results from two dimensional simulations of a "smooth" Eppler 398 wing profile and an inflatable or "bumpy" Eppler 398 wing profile. A discussion on computed flowfields follows for a number of test cases in an eort to understand the unique behavior seen in wind tunnel tests of inflatable wings. Numerical and experimental observations suggest that the flow
45th AIAA Aerospace Sciences Meeting and Exhibit, 2007
By its nature, the cache optimization of a computational fluid dynamics (CFD) code is most readil... more By its nature, the cache optimization of a computational fluid dynamics (CFD) code is most readily assessed on relatively simple geometries and on problems that only require the core routines. Having previously conducted cache optimization on two in-house codes at the ...
44th AIAA Aerospace Sciences Meeting and Exhibit, 2006
This paper presents an analysis of performance improvement of two CFD codes, the structured two-d... more This paper presents an analysis of performance improvement of two CFD codes, the structured two-dimensional code GHOST and the unstructured two-/three-dimensional code UNCLE, both in-house codes at the University of Kentucky, with the specific target of cache ...
... This process is 1Graduate Student, Dept. of Mechanical Engineering, [email protected], Student... more ... This process is 1Graduate Student, Dept. of Mechanical Engineering, [email protected], Student Member AIAA. ... KFC2 consists of commodity nodes each with a 2000+XP AMD Athlon processor and 256 MB RAM. The network is four-way channel bonded Fast Ethernet. ...
... Some Consequences of the Collision of a Comet and Jupiter Zahnle (NASAJARC), M.-M. Mac Low (U... more ... Some Consequences of the Collision of a Comet and Jupiter Zahnle (NASAJARC), M.-M. Mac Low (U. Chicago), CF Chyba (NASA/GSFC) At the time we write this, comet Shoemaker-Levy IX (1993e) is expected to strike Jupiter on July 21 1994 (IAU circular 5800; D. K Yeomans ...
Since its introduction in 1997, the Detached Eddy Simulation (DES) turbulence model has been used... more Since its introduction in 1997, the Detached Eddy Simulation (DES) turbulence model has been used successfully to simulate turbulence in an increasing number of computational fluid dynamics applications, primarily in aerospace engineering. The characteristics of DES - its compatibility with eddy viscosity models and its ability to smoothly transit from a Reynolds-Averaged Navier-Stokes (RANS) to a Large Eddy Simulation (LES) turbulence model - make it attractive as a potential turbulence model for atmospheric simulation. The current implementation of the model within the EPIC GCM is designed to provide turbulence closure from the planetary boundary layer to the upper atmosphere. We will present validation studies based on well-studied engineering and geophysical benchmark flows to examine the effects of DES model type (the Spalart-Allmaras or Menter SST version), boundary condition construction, coriolis forces, and problem scale. These validation tests are used to correct and calibrate the model, an iterative process that provides a more quantitative check of the DES techniques. Our main goal is to constrain a versatile planetary boundary-layer formulation using the full spectrum of available engineering data such that it provides good accuracy for a wide range of planetary applications, including Venus, Earth, Mars, Titan, and Triton. This work is sponsored by the NASA EPSCoR and Planetary Atmospheres Programs and the Kentucky Space Grant Consortium.
The use of actuators has been seen as an effective means for controlling flow over plates, airfoi... more The use of actuators has been seen as an effective means for controlling flow over plates, airfoils, and turbine blades. The use of plasma actuators is attractive since it lacks moving parts and can be easily integrated onto different geometries. There have been many experiments dealing with boundary layer control using passive elements, such as tripping the flow with surface roughness or other means of perturbing the surface without the addition of an external source of energy. There have also been many different active methods for controlling the boundary layer; examples include the use of piezoelectric actuators and morphing surfaces. Unlike many of the active methods listed above, plasma actuators are attractive because they can be easily implemented on a number of different geometries. Plasma Actuators have been proved, experimentally and numerically, as a potentially effective method for boundary layer control. This boundary layer control is driven by a body force vector tangent to the surface where the actuator is integrated. The purpose of this paper is to introduce the mathematical models used to describe the phenomena associated with plasma actuators, to implement them in a three-dimensional unstructured grid code, and to verify it by comparing numerical and experimental results.
43rd AIAA Aerospace Sciences Meeting and Exhibit, 2005
A cell-centered pressure based method is presented in this paper, and it is implemented in a new ... more A cell-centered pressure based method is presented in this paper, and it is implemented in a new two/three-dimensional parallel unstructured CFD code to meet the challenges of physical problems with complex geometries and complicated boundary conditions while maintaining high computational efficiency. The method uses a second order upwind scheme in space and a second order backward scheme for time accuracy. The SIMPLE algorithm in conjunction with the Rhie and Chow approach solves the continuity equation, minimizing undesirable pressure oscillations. The code is parallelized using METIS domain decomposition with good load balancing across computational nodes. In order to demonstrate the accuracy and performance of the current cell-centered pressure based method, several test cases are presented for validation such as two-dimensional incompressible flow past a flat plate, two/three-dimensional driven cavity flow, and two/three-dimensional flow over a circular cylinder. Notably, an extensive qualitative and quantitative study of two-dimensional flow over a circular cylinder for low Reynolds pressure-based method, several test cases are presented for validation such as two-dimensional incompressible flow past a flat plate, two/three-dimensional driven cavity flow, and two/three-dimensional flow over a circular cylinder.
The aerospace community is on the verge of a new generation of practical active flow control devi... more The aerospace community is on the verge of a new generation of practical active flow control devices from synthetic jets to plasma actuators. However, even as the mechanical challenges of implementing these systems seem attainable, the proper placement, orientation, and energy inputs to achieve the maximum benefit in a variety of flow conditions are unknown. Successful application of computational fluid dynamics (CFD) to this kind of control problem critically depends on an efficient searching algorithm for design optimization. Based on our previous research of single suction/blowing jet control on a NACA 0012 airfoil, the design parameters of a test multi-jet system are proposed. The convergence rates of a real-coded "Explicit Adaptive Range Normal Distribution" (EARND) genetic algorithm (GA) without/with Diversity Control are compared. The GA drives numerous CFD simulations, guiding the configuration of a suction jet and a blowing jet on the airfoil's upper surface. Reasonable optimum control values are determined within the control parameter range, suggesting the potential use of Evolutionary Algorithms to optimize these types of flow control applications.
A cell-centered pressure based method is presented in this paper, and it is implemented in a new ... more A cell-centered pressure based method is presented in this paper, and it is implemented in a new two/three-dimensional parallel unstructured CFD code to meet the challenges of physical problems with complex geometries and complicated boundary conditions while maintaining high computational efficiency. The method uses a second order upwind scheme in space and a second order backward scheme for time accuracy. The SIMPLE algorithm in conjunction with the Rhie and Chow approach solves the continuity equation, minimizing undesirable pressure oscillations. The code is parallelized using METIS domain decomposition with good load balancing across computational nodes. In order to demonstrate the accuracy and performance of the current cell-centered pressure based method, several test cases are presented for validation such as two-dimensional incompressible flow past a flat plate, two/three-dimensional driven cavity flow, and two/three-dimensional flow over a circular cylinder. Notably, an extensive qualitative and quantitative study of two-dimensional flow over a circular cylinder for low Reynolds pressure-based method, several test cases are presented for validation such as two-dimensional incompressible flow past a flat plate, two/three-dimensional driven cavity flow, and two/three-dimensional flow over a circular cylinder.
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Papers by Raymond Lebeau