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http://hdl.handle.net/10985/6626
Déplacement d'interfaces liquide - gaz sous l'effet d'un chauffage
DULUC, Marie-Christine; DARU, Virginie; ELAYYADI, Isam; LE QUÉRÉ, Patrick
On étudie numériquement une configuration diphasique monodimensionnelle assimilable à un actuateur thermique de petites dimensions dans laquelle deux lames d'air sont séparées entre elle par une lame d'eau liquide. On montre qu'il est possible de réaliser un déplacement de la lame liquide par chauffage d'une ou des deux parois en contact avec le gaz. Un modèle simple est développé permettant la mise en évidence des paramètres d'influence ainsi que des échelles de temps caractéristiques de la dynamique du système.
Mon, 01 Jan 2007 00:00:00 GMThttp://hdl.handle.net/10985/66262007-01-01T00:00:00ZDULUC, Marie-ChristineDARU, VirginieELAYYADI, IsamLE QUÉRÉ, PatrickOn étudie numériquement une configuration diphasique monodimensionnelle assimilable à un actuateur thermique de petites dimensions dans laquelle deux lames d'air sont séparées entre elle par une lame d'eau liquide. On montre qu'il est possible de réaliser un déplacement de la lame liquide par chauffage d'une ou des deux parois en contact avec le gaz. Un modèle simple est développé permettant la mise en évidence des paramètres d'influence ainsi que des échelles de temps caractéristiques de la dynamique du système.Modélisation quasi-dimensionnelle multizone de la phase de combustion dans un moteur à essence.
http://hdl.handle.net/10985/7435
Modélisation quasi-dimensionnelle multizone de la phase de combustion dans un moteur à essence.
KAPRIELIAN, Leslie; DEMOULIN, Marc; CINNELLA, Paola; DARU, Virginie
Quasi-dimensional models are needed in early design stages to evaluate engines sizing. They are based on principles of Thermodynamics and experimental correlations. Here, we improve the accuracy of the classical quasi-dimensional two-zone model by means of two successive modi cations. First, a third zone is added near the walls : in this zone, the gases burn more slowly due to heat losses to the walls. It allows to correctly simulate the attenuation of the combustion when the ame comes near the walls.Secondly, a multi-zone model is built to take into account temperature and concentration gradients in the ame. The models are validated by comparing heat release rates distributions predicted by the two-zone, the three-zone and the multi-zone models against experimental data.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/74352013-01-01T00:00:00ZKAPRIELIAN, LeslieDEMOULIN, MarcCINNELLA, PaolaDARU, VirginieQuasi-dimensional models are needed in early design stages to evaluate engines sizing. They are based on principles of Thermodynamics and experimental correlations. Here, we improve the accuracy of the classical quasi-dimensional two-zone model by means of two successive modi cations. First, a third zone is added near the walls : in this zone, the gases burn more slowly due to heat losses to the walls. It allows to correctly simulate the attenuation of the combustion when the ame comes near the walls.Secondly, a multi-zone model is built to take into account temperature and concentration gradients in the ame. The models are validated by comparing heat release rates distributions predicted by the two-zone, the three-zone and the multi-zone models against experimental data.A time semi-implicit scheme for the energy-balanced coupling of a shocked fluid flow with a deformable structure
http://hdl.handle.net/10985/10315
A time semi-implicit scheme for the energy-balanced coupling of a shocked fluid flow with a deformable structure
PUSCAS, Maria Adela; MONASSE, Laurent; ERN, Alexandre; TENAUD, Christian; MARIOTTI, Christian; DARU, Virginie
The objective of this work is to present a conservative coupling method between an inviscid compressible fluid and a deformable structure undergoing large displacements. The coupling method combines a cut-cell Finite Volume method, which is exactly conservative in the fluid, and a symplectic Discrete Element method for the deformable structure. A time semi-implicit approach is used for the computation of momentum and energy transfer between fluid and solid, the transfer being exactly balanced. The coupling method is exactly mass-conservative (up to round-off errors in the geometry of cut-cells) and exhibits numerically a long-time energy-preservation for the coupled system. The coupling method also exhibits consistency properties, such as conservation of uniform movement of both fluid and solid, absence of numerical roughness on a straight boundary, and preservation of a constant fluid state around a wall having tangential deformation velocity. The performance of the method is assessed on test cases involving shocked fluid flows interacting with two and three-dimensional deformable solids undergoing large displacements.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/103152015-01-01T00:00:00ZPUSCAS, Maria AdelaMONASSE, LaurentERN, AlexandreTENAUD, ChristianMARIOTTI, ChristianDARU, VirginieThe objective of this work is to present a conservative coupling method between an inviscid compressible fluid and a deformable structure undergoing large displacements. The coupling method combines a cut-cell Finite Volume method, which is exactly conservative in the fluid, and a symplectic Discrete Element method for the deformable structure. A time semi-implicit approach is used for the computation of momentum and energy transfer between fluid and solid, the transfer being exactly balanced. The coupling method is exactly mass-conservative (up to round-off errors in the geometry of cut-cells) and exhibits numerically a long-time energy-preservation for the coupled system. The coupling method also exhibits consistency properties, such as conservation of uniform movement of both fluid and solid, absence of numerical roughness on a straight boundary, and preservation of a constant fluid state around a wall having tangential deformation velocity. The performance of the method is assessed on test cases involving shocked fluid flows interacting with two and three-dimensional deformable solids undergoing large displacements.Fast acoustic streaming in standing waves : Generation of an additional outer streaming cell
http://hdl.handle.net/10985/8595
Fast acoustic streaming in standing waves : Generation of an additional outer streaming cell
REYT, Ida; BAILLIET, Hélène; MOREAU, Solène; VALIERE, Jean-Christophe; BALTEAN-CARLÈS, Diana; WEISMAN, Catherine; DARU, Virginie
Rayleigh streaming in a cylindrical acoustic standing waveguide is studied both experimentally and numerically for nonlinear Reynolds numbers from 1 to 30. Streaming velocity is measured by means of laser Doppler velocimetry in a cylindrical resonator filled with air at atmospheric pressure at high intensity sound levels. The compressible Navier-Stokes equations are solved numerically with high resolution finite difference schemes. The resonator is excited by shaking it along the axis at imposed frequency. Results of measurements and of numerical calculation are compared with results given in the literature and with each other. As expected, the axial streaming velocity measured and calculated agrees reasonably well with the slow streaming theory for small ReNL but deviates significantly from such predictions for fast streaming (ReNL > 1). Both experimental and numerical results show that when ReNL is increased, the center of the outer streaming cells are pushed toward the acoustic velocity nodes until counter-rotating additional vortices are generated near the acoustic velocity antinodes.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/85952013-01-01T00:00:00ZREYT, IdaBAILLIET, HélèneMOREAU, SolèneVALIERE, Jean-ChristopheBALTEAN-CARLÈS, DianaWEISMAN, CatherineDARU, VirginieRayleigh streaming in a cylindrical acoustic standing waveguide is studied both experimentally and numerically for nonlinear Reynolds numbers from 1 to 30. Streaming velocity is measured by means of laser Doppler velocimetry in a cylindrical resonator filled with air at atmospheric pressure at high intensity sound levels. The compressible Navier-Stokes equations are solved numerically with high resolution finite difference schemes. The resonator is excited by shaking it along the axis at imposed frequency. Results of measurements and of numerical calculation are compared with results given in the literature and with each other. As expected, the axial streaming velocity measured and calculated agrees reasonably well with the slow streaming theory for small ReNL but deviates significantly from such predictions for fast streaming (ReNL > 1). Both experimental and numerical results show that when ReNL is increased, the center of the outer streaming cells are pushed toward the acoustic velocity nodes until counter-rotating additional vortices are generated near the acoustic velocity antinodes.Two-dimensional numerical simulations of nonlinear acoustic streaming in standing waves
http://hdl.handle.net/10985/8594
Two-dimensional numerical simulations of nonlinear acoustic streaming in standing waves
DARU, Virginie; BALTEAN-CARLÈS, Diana; WEISMAN, Catherine; DEBESSE, Philippe; GANDIKOTA, Gurunath
Numerical simulations of compressible Navier–Stokes equations in closed two-dimensional channels are performed. A plane standing wave is excited inside the channel and the associated acoustic streaming is investigated for high intensity waves, in the nonlinear streaming regime. Significant distortion of streaming cells is observed, with the centers of streaming cells pushed toward the end-walls. The mean temperature evolution associated with the streaming motion is also investigated.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/85942013-01-01T00:00:00ZDARU, VirginieBALTEAN-CARLÈS, DianaWEISMAN, CatherineDEBESSE, PhilippeGANDIKOTA, GurunathNumerical simulations of compressible Navier–Stokes equations in closed two-dimensional channels are performed. A plane standing wave is excited inside the channel and the associated acoustic streaming is investigated for high intensity waves, in the nonlinear streaming regime. Significant distortion of streaming cells is observed, with the centers of streaming cells pushed toward the end-walls. The mean temperature evolution associated with the streaming motion is also investigated.On wall pressure fluctuations and their coupling with vortex dynamicsin a separate d–reattache d turbulent flow over a blunt flat plate
http://hdl.handle.net/10985/17517
On wall pressure fluctuations and their coupling with vortex dynamicsin a separate d–reattache d turbulent flow over a blunt flat plate
TENAUD, C; PODVIN, B; FRAIGNEAU, Y; DARU, Virginie
This study deals with the numerical predictions through Large-Eddy Simulation ( LES ) of the separated–reattached turbulent flow over a blunt flat plate for analyzing main coherent structure features and theirrelation to the unsteady pressure field. A compressible approach that inherently includes acoustic prop- agation is here followed to describe the relationship between pressure fluctuations and vortex dynam- ics around the separation bubble. The objective of the present work is then to contribute to a betterunderstanding of the coupling between the vortex dynamics and the wall pressure fluctuations. The fil- tered compressible Navier–Stokes equations are then solved with a numerical method that follows a Lax–Wendroffapproach to recover a high accuracy in both time and space. For validations, the present numer- ical results are compared to experimental measurements, coming from both the Pprime laboratory (Sicotel al., 2012) and the literature (Cherry et al., 1984; Kiya and Sasaki, 1985; Tafti and Vanka,1991; Sicotet al., 2012). Our numerical results very well predict mean and fluctuating pressure and velocity fields.Flapping, shedding as well as Kelvin–Helmholtz characteristic frequencies educed by present simulationsare in very good agreement with the experimental values generally admitted. These characteristic modesare also visible on unsteady pressure signatures even far away from the separation. Spectral, POD andEPOD (extended POD) analyses are then applied to these numerical data to enhance the salient featuresof the pressure and velocity fields, especially the unsteady wall pressure in connection with either thevortex shedding or the low frequency shear-layer flapping. A contribution to the understanding of thecoupling between wall pressure fluctuations and eddy vortices is finally proposed.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10985/175172016-01-01T00:00:00ZTENAUD, CPODVIN, BFRAIGNEAU, YDARU, VirginieThis study deals with the numerical predictions through Large-Eddy Simulation ( LES ) of the separated–reattached turbulent flow over a blunt flat plate for analyzing main coherent structure features and theirrelation to the unsteady pressure field. A compressible approach that inherently includes acoustic prop- agation is here followed to describe the relationship between pressure fluctuations and vortex dynam- ics around the separation bubble. The objective of the present work is then to contribute to a betterunderstanding of the coupling between the vortex dynamics and the wall pressure fluctuations. The fil- tered compressible Navier–Stokes equations are then solved with a numerical method that follows a Lax–Wendroffapproach to recover a high accuracy in both time and space. For validations, the present numer- ical results are compared to experimental measurements, coming from both the Pprime laboratory (Sicotel al., 2012) and the literature (Cherry et al., 1984; Kiya and Sasaki, 1985; Tafti and Vanka,1991; Sicotet al., 2012). Our numerical results very well predict mean and fluctuating pressure and velocity fields.Flapping, shedding as well as Kelvin–Helmholtz characteristic frequencies educed by present simulationsare in very good agreement with the experimental values generally admitted. These characteristic modesare also visible on unsteady pressure signatures even far away from the separation. Spectral, POD andEPOD (extended POD) analyses are then applied to these numerical data to enhance the salient featuresof the pressure and velocity fields, especially the unsteady wall pressure in connection with either thevortex shedding or the low frequency shear-layer flapping. A contribution to the understanding of thecoupling between wall pressure fluctuations and eddy vortices is finally proposed.An unexpected balance between outer Rayleigh streaming sources
http://hdl.handle.net/10985/18011
An unexpected balance between outer Rayleigh streaming sources
BALTEAN-CARLÈS, Diana; DARU, Virginie; WEISMAN, Catherine; TABAKOVA, S.; BAILLIET, Hélène
Acoustic streaming generated by a plane standing wave between two infinite plates or inside a cylindrical tube is considered, under the isentropic flow assumption. A two-dimensional analysis is performed in the linear case of slow streaming motion, based on analytical formal solutions of separate problems, each associated with a specific source term (Reynolds stress term). In order to obtain these analytical solutions, a necessary geometrical hypothesis is that (R/L)2 << 1, where R and L are the guide half-width (or radius) and length. The effect of the two source terms classically taken into account is quantified in order to derive the dependence of the maximum axial streaming velocity on the axis as a function of the ratio R/δν , where δν is the acoustic boundary layer thickness. The effect of two other source terms that are usually neglected, is then analysed. It is found that one of these terms can generate a counter-rotating streaming flow. While negligible for very narrow guides, this term can become important for some values of the aspect ratio L/R.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/10985/180112019-01-01T00:00:00ZBALTEAN-CARLÈS, DianaDARU, VirginieWEISMAN, CatherineTABAKOVA, S.BAILLIET, HélèneAcoustic streaming generated by a plane standing wave between two infinite plates or inside a cylindrical tube is considered, under the isentropic flow assumption. A two-dimensional analysis is performed in the linear case of slow streaming motion, based on analytical formal solutions of separate problems, each associated with a specific source term (Reynolds stress term). In order to obtain these analytical solutions, a necessary geometrical hypothesis is that (R/L)2 << 1, where R and L are the guide half-width (or radius) and length. The effect of the two source terms classically taken into account is quantified in order to derive the dependence of the maximum axial streaming velocity on the axis as a function of the ratio R/δν , where δν is the acoustic boundary layer thickness. The effect of two other source terms that are usually neglected, is then analysed. It is found that one of these terms can generate a counter-rotating streaming flow. While negligible for very narrow guides, this term can become important for some values of the aspect ratio L/R.Inertial effects on acoustic Rayleigh streaming flow: Transient and established regimes
http://hdl.handle.net/10985/17478
Inertial effects on acoustic Rayleigh streaming flow: Transient and established regimes
DARU, Virginie; WEISMAN, Catherine; BALTEAN-CARLÈS, Diana; REYT, Ida; BAILLIET, Hélène
The effect of inertia on Rayleigh streaming generated inside a cylindrical resonator where a mono-frequency standing wave is imposed, is investigated numerically and experimentally. To this effect, time evolutions of streaming cells in the near wall region and in the resonator core are analyzed. An analogy with the lid-driven cavity in a cylindrical geometry is presented in order to analyze the physical meanings of the characteristic times. Inertial effects on the established streaming flow pattern are then investigated numerically using a code solving the time averaged Navier–Stokes compressible equations, where a mono-frequency acoustic flow field is used to compute the source terms. It is shown that inertia of streaming cannot be considered as the leading phenomenon to explain the mutation of streaming at high acoustic levels.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10985/174782017-01-01T00:00:00ZDARU, VirginieWEISMAN, CatherineBALTEAN-CARLÈS, DianaREYT, IdaBAILLIET, HélèneThe effect of inertia on Rayleigh streaming generated inside a cylindrical resonator where a mono-frequency standing wave is imposed, is investigated numerically and experimentally. To this effect, time evolutions of streaming cells in the near wall region and in the resonator core are analyzed. An analogy with the lid-driven cavity in a cylindrical geometry is presented in order to analyze the physical meanings of the characteristic times. Inertial effects on the established streaming flow pattern are then investigated numerically using a code solving the time averaged Navier–Stokes compressible equations, where a mono-frequency acoustic flow field is used to compute the source terms. It is shown that inertia of streaming cannot be considered as the leading phenomenon to explain the mutation of streaming at high acoustic levels.Acoustic and streaming velocity components in a resonant waveguide at high acoustic levels
http://hdl.handle.net/10985/17522
Acoustic and streaming velocity components in a resonant waveguide at high acoustic levels
DARU, Virginie; REYT, Ida; BAILLIET, Hélène; WEISMAN, Catherine; BALTEAN-CARLÈS, Diana
Rayleigh streaming is a steady flow generated by the interaction between an acoustic wave and a solid wall, generally assumed to be second order in a Mach number expansion. Acoustic streaming is well known in the case of a stationary plane wave at low amplitude: it has a half-wavelength spatial periodicity and the maximum axial streaming velocity is a quadratic function of the acoustic velocity amplitude at antinode. For higher acoustic levels, additional streaming cells have been observed. Results of laser Doppler velocimetry measurements are here compared to direct numerical simulations. The evolution of axial and radial velocity components for both acoustic and streaming velocities is studied from low to high acoustic amplitudes. Two streaming flow regimes are pointed out, the axial streaming dependency on acoustics going from quadratic to linear. The evolution of streaming flow is different for outer cells and for inner cells. Also, the hypothesis of radial streaming velocity being of second order in a Mach number expansion, is not valid at high amplitudes. The change of regime occurs when the radial streaming velocity amplitude becomes larger than the radial acoustic velocity amplitude, high levels being therefore characterized by nonlinear interaction of the different velocity components.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10985/175222017-01-01T00:00:00ZDARU, VirginieREYT, IdaBAILLIET, HélèneWEISMAN, CatherineBALTEAN-CARLÈS, DianaRayleigh streaming is a steady flow generated by the interaction between an acoustic wave and a solid wall, generally assumed to be second order in a Mach number expansion. Acoustic streaming is well known in the case of a stationary plane wave at low amplitude: it has a half-wavelength spatial periodicity and the maximum axial streaming velocity is a quadratic function of the acoustic velocity amplitude at antinode. For higher acoustic levels, additional streaming cells have been observed. Results of laser Doppler velocimetry measurements are here compared to direct numerical simulations. The evolution of axial and radial velocity components for both acoustic and streaming velocities is studied from low to high acoustic amplitudes. Two streaming flow regimes are pointed out, the axial streaming dependency on acoustics going from quadratic to linear. The evolution of streaming flow is different for outer cells and for inner cells. Also, the hypothesis of radial streaming velocity being of second order in a Mach number expansion, is not valid at high amplitudes. The change of regime occurs when the radial streaming velocity amplitude becomes larger than the radial acoustic velocity amplitude, high levels being therefore characterized by nonlinear interaction of the different velocity components.