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Papers by Prasanth Kutchu
Journal of Fluid Mechanics, Jan 1, 2004
Theoretical and Computational Fluid Dynamics, Jan 1, 1994
High-order finite-difference schemes are less dispersive and dissipative but, at the same time, m... more High-order finite-difference schemes are less dispersive and dissipative but, at the same time, more isotropic than low-order schemes. They are well suited for solving computational acoustics problems. High-order finite-difference equations, however, support extraneous wave solutions which bear no resemblance to the exact solution of the original partial differential equations. These extraneous wave solutions, which invariably degrade the quality of the numerical solutions, are usually generated when solid-wall boundary conditions are imposed. A set of numerical boundary conditions simulating the presence of a solid wall for high-order finitedifference schemes using a minimum number of ghost values is proposed. The effectiveness of the numerical boundary conditions in producing quality solutions is analyzed and demonstrated by comparing the results of direct numerical simulations and exact solutions.
Journal of Computational …, Jan 1, 1997
This paper describes the application of a three dimensional Computational Aeroacoustics (CAA) met... more This paper describes the application of a three dimensional Computational Aeroacoustics (CAA) methodology to the prediction of jet noise. The technique has been implemented using parallel computers. In this approach the non-linear disturbance equations are solved in a conservative form using a nite-di erence based technique. A fourth order optimized Dispersion Relation Preserving (DRP) scheme is used for spatial discretization and a fourth order classical Runge-Kutta scheme is employed for temporal discretization. The threedimensional CAA code has been parallelized using a domain decomposition strategy in the streamwise direction. The calculations are carried out on both IBM-SP2 and SGI Power-Challenge parallel computers using Message Passing Interface (MPI) routines to facilitate exchange of boundary data between adjacent nodes (processors). Excellent parallel performance has been obtained using the present code. Acoustic results are presented for a perfectly expanded supersonic axisymmetric jet under harmonic and random inlet conditions. Results are given for both the instantaneous and averaged ow and acoustic variables. Comparisons are made between the predictions and experimental data.
Unknown, Jan 1, 1994
Abstract Generalized functions have many applications in science and engineering. One useful aspe... more Abstract Generalized functions have many applications in science and engineering. One useful aspect is that discontinuous functions can be handled as easily as continuous or differentiable functions and provide a powerful tool in formulating and solving many ...
Theoretical and Computational Fluid Dynamics, Jan 1, 1994
A new technique for the numerical analysis of aerodynamic noise generation is developed. The appr... more A new technique for the numerical analysis of aerodynamic noise generation is developed. The approach involves first solving for the time-dependent incompressible flow for the given geometry. A "hydrodynamic" density correction to the constant incompressible density is then calculated from knowledge of the incompressible pressure fluctuations. The compressible flow solution is finally obtained by considering perturbations about the "corrected" incompressible flow. This fully nonlinear technique, which is tailored to extract the relevant acoustic fluctuations, appears to be an efficient approach to the numerical analysis of aerodynamic noise generation, particularly in viscous flows. Applications of this technique to some classical acoustic problems of interest, including some with moderately high subsonic Mach numbers, are presented to validate the approach. The technique is then applied to a fully viscous problem where sound is generated by the flow dynamics.
… and Maneuvering Propulsion: Research Status and …, Jan 1, 1984
... Bibliographic Code: 1984aiaa.confY....S. Abstract. This paper provides an assessment from an ... more ... Bibliographic Code: 1984aiaa.confY....S. Abstract. This paper provides an assessment from an experimental point of view of the present understanding of high speed jet noise primarily as it pertains to shock containing supersonic jet plumes. ...
Journal of fluids engineering, Jan 1, 1994
Progress in Aerospace Sciences, Jan 1, 2004
Computational approaches are being developed to study a range of problems in aeroacoustics. These... more Computational approaches are being developed to study a range of problems in aeroacoustics. These aeroacoustic problems may be classified based on the physical processes responsible for the sound radiation, and range from linear problems of radiation, refraction, and scattering in known base flows or by solid bodies, to sound generation by turbulence. In this article, we focus mainly on the challenges and successes associated with numerically simulating sound generation by turbulent flows.
AIAA journal, Jan 1, 1995
Computational fluid dynamics (CFD) has made tremendous progress especially in aerodynamics and ai... more Computational fluid dynamics (CFD) has made tremendous progress especially in aerodynamics and aircraft design over the past 20 years. An obvious question to ask is "why not use CFD methods to solve aeroacoustics problems?" Most aerodynamics problems are time independent, whereas aeroacoustics problems are, by definition, time dependent. The nature, characteristics, and objectives of aeroacoustics problems are also quite different from the commonly encountered CFD problems. There are computational issues that are unique to aeroacoustics. For these reasons computational aeroacoustics requires somewhat independent thinking and development. The objectives of this paper are twofold. First, issues pertinent to aeroacoustics that may or may not be relevant to computational aerodynamics are discussed. The second objective is to review computational methods developed recently that are designed especially for computational aeroacoustics applications. Some of the computational methods to be reviewed are quite different from traditional CFD methods. They should be of interest to the CFD and fluid dynamics communities.
New York, McGraw-Hill International Book Co., …, Jan 1, 1976
Abstract A review of the acoustics of moving media is provided, taking into account a derivation ... more Abstract A review of the acoustics of moving media is provided, taking into account a derivation of basic equations, wave-like solutions of acoustic equations, the solutions of acoustic equations by superposition of elementary sources, the source distribution in ...
Journal of Fluid Mechanics, Jan 1, 2004
Theoretical and Computational Fluid Dynamics, Jan 1, 1994
High-order finite-difference schemes are less dispersive and dissipative but, at the same time, m... more High-order finite-difference schemes are less dispersive and dissipative but, at the same time, more isotropic than low-order schemes. They are well suited for solving computational acoustics problems. High-order finite-difference equations, however, support extraneous wave solutions which bear no resemblance to the exact solution of the original partial differential equations. These extraneous wave solutions, which invariably degrade the quality of the numerical solutions, are usually generated when solid-wall boundary conditions are imposed. A set of numerical boundary conditions simulating the presence of a solid wall for high-order finitedifference schemes using a minimum number of ghost values is proposed. The effectiveness of the numerical boundary conditions in producing quality solutions is analyzed and demonstrated by comparing the results of direct numerical simulations and exact solutions.
Journal of Computational …, Jan 1, 1997
This paper describes the application of a three dimensional Computational Aeroacoustics (CAA) met... more This paper describes the application of a three dimensional Computational Aeroacoustics (CAA) methodology to the prediction of jet noise. The technique has been implemented using parallel computers. In this approach the non-linear disturbance equations are solved in a conservative form using a nite-di erence based technique. A fourth order optimized Dispersion Relation Preserving (DRP) scheme is used for spatial discretization and a fourth order classical Runge-Kutta scheme is employed for temporal discretization. The threedimensional CAA code has been parallelized using a domain decomposition strategy in the streamwise direction. The calculations are carried out on both IBM-SP2 and SGI Power-Challenge parallel computers using Message Passing Interface (MPI) routines to facilitate exchange of boundary data between adjacent nodes (processors). Excellent parallel performance has been obtained using the present code. Acoustic results are presented for a perfectly expanded supersonic axisymmetric jet under harmonic and random inlet conditions. Results are given for both the instantaneous and averaged ow and acoustic variables. Comparisons are made between the predictions and experimental data.
Unknown, Jan 1, 1994
Abstract Generalized functions have many applications in science and engineering. One useful aspe... more Abstract Generalized functions have many applications in science and engineering. One useful aspect is that discontinuous functions can be handled as easily as continuous or differentiable functions and provide a powerful tool in formulating and solving many ...
Theoretical and Computational Fluid Dynamics, Jan 1, 1994
A new technique for the numerical analysis of aerodynamic noise generation is developed. The appr... more A new technique for the numerical analysis of aerodynamic noise generation is developed. The approach involves first solving for the time-dependent incompressible flow for the given geometry. A "hydrodynamic" density correction to the constant incompressible density is then calculated from knowledge of the incompressible pressure fluctuations. The compressible flow solution is finally obtained by considering perturbations about the "corrected" incompressible flow. This fully nonlinear technique, which is tailored to extract the relevant acoustic fluctuations, appears to be an efficient approach to the numerical analysis of aerodynamic noise generation, particularly in viscous flows. Applications of this technique to some classical acoustic problems of interest, including some with moderately high subsonic Mach numbers, are presented to validate the approach. The technique is then applied to a fully viscous problem where sound is generated by the flow dynamics.
… and Maneuvering Propulsion: Research Status and …, Jan 1, 1984
... Bibliographic Code: 1984aiaa.confY....S. Abstract. This paper provides an assessment from an ... more ... Bibliographic Code: 1984aiaa.confY....S. Abstract. This paper provides an assessment from an experimental point of view of the present understanding of high speed jet noise primarily as it pertains to shock containing supersonic jet plumes. ...
Journal of fluids engineering, Jan 1, 1994
Progress in Aerospace Sciences, Jan 1, 2004
Computational approaches are being developed to study a range of problems in aeroacoustics. These... more Computational approaches are being developed to study a range of problems in aeroacoustics. These aeroacoustic problems may be classified based on the physical processes responsible for the sound radiation, and range from linear problems of radiation, refraction, and scattering in known base flows or by solid bodies, to sound generation by turbulence. In this article, we focus mainly on the challenges and successes associated with numerically simulating sound generation by turbulent flows.
AIAA journal, Jan 1, 1995
Computational fluid dynamics (CFD) has made tremendous progress especially in aerodynamics and ai... more Computational fluid dynamics (CFD) has made tremendous progress especially in aerodynamics and aircraft design over the past 20 years. An obvious question to ask is "why not use CFD methods to solve aeroacoustics problems?" Most aerodynamics problems are time independent, whereas aeroacoustics problems are, by definition, time dependent. The nature, characteristics, and objectives of aeroacoustics problems are also quite different from the commonly encountered CFD problems. There are computational issues that are unique to aeroacoustics. For these reasons computational aeroacoustics requires somewhat independent thinking and development. The objectives of this paper are twofold. First, issues pertinent to aeroacoustics that may or may not be relevant to computational aerodynamics are discussed. The second objective is to review computational methods developed recently that are designed especially for computational aeroacoustics applications. Some of the computational methods to be reviewed are quite different from traditional CFD methods. They should be of interest to the CFD and fluid dynamics communities.
New York, McGraw-Hill International Book Co., …, Jan 1, 1976
Abstract A review of the acoustics of moving media is provided, taking into account a derivation ... more Abstract A review of the acoustics of moving media is provided, taking into account a derivation of basic equations, wave-like solutions of acoustic equations, the solutions of acoustic equations by superposition of elementary sources, the source distribution in ...