Notes on Numerical Fluid Mechanics and Multidisciplinary Design (NNFM), 2006
ABSTRACT The objective of the present study is to provide advanced statistical turbulence modelli... more ABSTRACT The objective of the present study is to provide advanced statistical turbulence modelling closures for aerodynamic flows around bodies at high Reynolds number. This study has been carried out by means of theoretical analysis based on the IMFT’s experimental data-base (see part 2 of the book). The two-equation modelling has been reconsidered in the context of the URANS/Organised Eddy Simulation, OES approach in respect of modifying the turbulence length scale involved in the eddy-diffusion coefficient. This has been done from second-order moment closures considerations in OES, from DNS and from the experimental sspectra for the turbulence fluctuating energy.
Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 2010
ABSTRACT The present study presents numerical simulations and turbulence modelling of the flow ar... more ABSTRACT The present study presents numerical simulations and turbulence modelling of the flow around a NACA0012 airfoil including a deflected aileron. The results are compared with experiments that have been performed in the N-3 wind tunnel of the Institute of Aviation (IoA), Warsaw. The experiment focused on unsteady flow characteristics and buffet phenomena arising as the result of the transonic shock wave / boundary layer interaction (SWBLI). The transonic buffet is a natural and self-sustaining oscillation of the shock wave and separated flow region, caused by pressure fluctuation. The first objective is to capture the transonic buffet unsteadiness by means of URANS and DES turbulence modelling approaches. Secondly, the periodic flap oscillation has been used to modify the oscillation amplitudes towards an outlook of attenuation of the transonic buffet.
Notes on Numerical Fluid Mechanics and Multidisciplinary Design (NNFM), 2006
The main objective of the present study is to analyse the turbulence properties in unsteady, stro... more The main objective of the present study is to analyse the turbulence properties in unsteady, strongly detached flows and to provide a database for improvement and validation of turbulence models, concerning the present class of non-equilibrium flows. The flow around a circular cylinder with a low aspect ratio (L/D=4.8) and a high blockage coefficient (D/H=0.208) is investigated. This confined environment
This paper provides a study of the dynamic stall of a pitching airfoil and of a pitching and hori... more This paper provides a study of the dynamic stall of a pitching airfoil and of a pitching and horizontally oscillating airfoil at 105 Reynolds number by means of nbumerical simulation. Three turbulence models are compared in both cases: URANS Spalart-Allmaras model, URANS k—ε Chien model and URANS=OES model. results are in accordance with experimental data but spalart model seems to
Progress in Computational Flow-Structure Interaction, 2003
ABSTRACT The current main chapter contains 14 contributions which cover all applications treated ... more ABSTRACT The current main chapter contains 14 contributions which cover all applications treated within the context of UNSI. Emphasis was placed on cross comparison of data in order to support potential scientists in their own work on validation/verification of all these test cases.
... More recently, the early phase of the establishment of the flow around a cylinder started imp... more ... More recently, the early phase of the establishment of the flow around a cylinder started impulsively into rotation and translation was investigated experimentally by Coutanceau and Ménard [9], and numerically by Badr and Dennis [3], for moderate Reynolds numbers (Re Ä ...
... second-order closure, [9], involving Shima's damping function at the vicinity of the... more ... second-order closure, [9], involving Shima's damping function at the vicinity of the wall [10]. The test-case of a NACA0012 airfoil at 20 ... Part of this work is carried out on the basis of CPU allocations of the national com-puter centres of France CINES, CALMIP and IDRIS. ...
The onset of the secondary instability and the successive steps ofthe 3D transition to turbulence... more The onset of the secondary instability and the successive steps ofthe 3D transition to turbulence are examined in the flow around a wing of NACA0012 section, constant along the spanwise direction. The wing is placed in a uniform flow upstream, at 20 of incidence and at the Reynolds number of 800. The spanwise length is equal to four chords. The
A combined experimental and numerical investigation of transonic shock wave/boundary layer intera... more A combined experimental and numerical investigation of transonic shock wave/boundary layer interaction over a wall-mounted bump has been undertaken looking at the details of the flow and the capability of CFD in predicting such complex, yet fundamental, aerodynamic interactions. The transonic wind tunnel of the Queens University of Belfast (QUB) has been employed for experiments that were combined with CFD
In this paper, we study the motion of a circular cylinder freely falling in a channel under the a... more In this paper, we study the motion of a circular cylinder freely falling in a channel under the action of gravity parallel to the wall. The fixed parameters of the study are the cylinder diameter to channel width ratio, D/d = 3.3, and the fluid to particle density ratio, ß = 2. The varying parameters are the initial position (in
ABSTRACT This article proposes a review of recent and current developments in the modeling and ad... more ABSTRACT This article proposes a review of recent and current developments in the modeling and advanced numerical methods used to simulate large-size systems involving multi-physics in the field of mechanics. It addresses the complex issue of stability analysis of dynamical systems submitted to external turbulent flows and aims to establish accurate stability maps applicable to heat exchanger design. The purpose is to provide dimensionless stability limit modeling that is suitable for a variety of configurations and is as accurate as possible in spite of the large scale of the systems to be considered. The challenge lies in predicting local effects that may impact global systems. A combination of several strategies that are suited concurrently to multi-physics, multi-scale and large-size system computation is therefore required. Based on empirical concepts, the heuristic models currently used in the framework of standard stability analysis suffer from a lack of predictive capabilities. On the other hand, numerical approaches based on fully-coupled fluid–solid dynamics system computation remain expensive due to the multi-physics patterns of physics and the large number of degrees of freedom involved. In this context, since experimentation cannot be achieved and numerical simulation is unavoidable but prohibitive, a hybrid strategy is proposed in order to take advantage of both numerical local solutions and empirical global solutions.
Notes on Numerical Fluid Mechanics and Multidisciplinary Design (NNFM), 2006
ABSTRACT The objective of the present study is to provide advanced statistical turbulence modelli... more ABSTRACT The objective of the present study is to provide advanced statistical turbulence modelling closures for aerodynamic flows around bodies at high Reynolds number. This study has been carried out by means of theoretical analysis based on the IMFT’s experimental data-base (see part 2 of the book). The two-equation modelling has been reconsidered in the context of the URANS/Organised Eddy Simulation, OES approach in respect of modifying the turbulence length scale involved in the eddy-diffusion coefficient. This has been done from second-order moment closures considerations in OES, from DNS and from the experimental sspectra for the turbulence fluctuating energy.
Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 2010
ABSTRACT The present study presents numerical simulations and turbulence modelling of the flow ar... more ABSTRACT The present study presents numerical simulations and turbulence modelling of the flow around a NACA0012 airfoil including a deflected aileron. The results are compared with experiments that have been performed in the N-3 wind tunnel of the Institute of Aviation (IoA), Warsaw. The experiment focused on unsteady flow characteristics and buffet phenomena arising as the result of the transonic shock wave / boundary layer interaction (SWBLI). The transonic buffet is a natural and self-sustaining oscillation of the shock wave and separated flow region, caused by pressure fluctuation. The first objective is to capture the transonic buffet unsteadiness by means of URANS and DES turbulence modelling approaches. Secondly, the periodic flap oscillation has been used to modify the oscillation amplitudes towards an outlook of attenuation of the transonic buffet.
Notes on Numerical Fluid Mechanics and Multidisciplinary Design (NNFM), 2006
The main objective of the present study is to analyse the turbulence properties in unsteady, stro... more The main objective of the present study is to analyse the turbulence properties in unsteady, strongly detached flows and to provide a database for improvement and validation of turbulence models, concerning the present class of non-equilibrium flows. The flow around a circular cylinder with a low aspect ratio (L/D=4.8) and a high blockage coefficient (D/H=0.208) is investigated. This confined environment
This paper provides a study of the dynamic stall of a pitching airfoil and of a pitching and hori... more This paper provides a study of the dynamic stall of a pitching airfoil and of a pitching and horizontally oscillating airfoil at 105 Reynolds number by means of nbumerical simulation. Three turbulence models are compared in both cases: URANS Spalart-Allmaras model, URANS k—ε Chien model and URANS=OES model. results are in accordance with experimental data but spalart model seems to
Progress in Computational Flow-Structure Interaction, 2003
ABSTRACT The current main chapter contains 14 contributions which cover all applications treated ... more ABSTRACT The current main chapter contains 14 contributions which cover all applications treated within the context of UNSI. Emphasis was placed on cross comparison of data in order to support potential scientists in their own work on validation/verification of all these test cases.
... More recently, the early phase of the establishment of the flow around a cylinder started imp... more ... More recently, the early phase of the establishment of the flow around a cylinder started impulsively into rotation and translation was investigated experimentally by Coutanceau and Ménard [9], and numerically by Badr and Dennis [3], for moderate Reynolds numbers (Re Ä ...
... second-order closure, [9], involving Shima's damping function at the vicinity of the... more ... second-order closure, [9], involving Shima's damping function at the vicinity of the wall [10]. The test-case of a NACA0012 airfoil at 20 ... Part of this work is carried out on the basis of CPU allocations of the national com-puter centres of France CINES, CALMIP and IDRIS. ...
The onset of the secondary instability and the successive steps ofthe 3D transition to turbulence... more The onset of the secondary instability and the successive steps ofthe 3D transition to turbulence are examined in the flow around a wing of NACA0012 section, constant along the spanwise direction. The wing is placed in a uniform flow upstream, at 20 of incidence and at the Reynolds number of 800. The spanwise length is equal to four chords. The
A combined experimental and numerical investigation of transonic shock wave/boundary layer intera... more A combined experimental and numerical investigation of transonic shock wave/boundary layer interaction over a wall-mounted bump has been undertaken looking at the details of the flow and the capability of CFD in predicting such complex, yet fundamental, aerodynamic interactions. The transonic wind tunnel of the Queens University of Belfast (QUB) has been employed for experiments that were combined with CFD
In this paper, we study the motion of a circular cylinder freely falling in a channel under the a... more In this paper, we study the motion of a circular cylinder freely falling in a channel under the action of gravity parallel to the wall. The fixed parameters of the study are the cylinder diameter to channel width ratio, D/d = 3.3, and the fluid to particle density ratio, ß = 2. The varying parameters are the initial position (in
ABSTRACT This article proposes a review of recent and current developments in the modeling and ad... more ABSTRACT This article proposes a review of recent and current developments in the modeling and advanced numerical methods used to simulate large-size systems involving multi-physics in the field of mechanics. It addresses the complex issue of stability analysis of dynamical systems submitted to external turbulent flows and aims to establish accurate stability maps applicable to heat exchanger design. The purpose is to provide dimensionless stability limit modeling that is suitable for a variety of configurations and is as accurate as possible in spite of the large scale of the systems to be considered. The challenge lies in predicting local effects that may impact global systems. A combination of several strategies that are suited concurrently to multi-physics, multi-scale and large-size system computation is therefore required. Based on empirical concepts, the heuristic models currently used in the framework of standard stability analysis suffer from a lack of predictive capabilities. On the other hand, numerical approaches based on fully-coupled fluid–solid dynamics system computation remain expensive due to the multi-physics patterns of physics and the large number of degrees of freedom involved. In this context, since experimentation cannot be achieved and numerical simulation is unavoidable but prohibitive, a hybrid strategy is proposed in order to take advantage of both numerical local solutions and empirical global solutions.
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