We detail some of the understudied aspects of the flow inside and around the Hexactinellid Sponge Euplectella aspergillum.By leveraging the flexibility of the Lattice Boltzmann Method,High Performance Computing simula...We detail some of the understudied aspects of the flow inside and around the Hexactinellid Sponge Euplectella aspergillum.By leveraging the flexibility of the Lattice Boltzmann Method,High Performance Computing simulations are performed to dissect the complex conditions corresponding to the actual environment at the bottom of the ocean,at depths between 100 and 1,000 m.These large-scale simulations unveil potential clues on the evolutionary adaptations of these deep-sea sponges in response to the surrounding fluid flow,and they open the path to future investigations at the interface between physics,engineering and biology.展开更多
DSFD 2021,the 30th edition of the Discrete Simulation of Fluid Dynamics,took place again at University of Tuscia,Viterbo,Italy on September 13-172021.Due to the persisting uncertainties associated with the COVID-19 pa...DSFD 2021,the 30th edition of the Discrete Simulation of Fluid Dynamics,took place again at University of Tuscia,Viterbo,Italy on September 13-172021.Due to the persisting uncertainties associated with the COVID-19 pandemics it was again organised virtually,like the preceding one.展开更多
This work is concerned with the modelling of the interaction of fluid flow with flexibly supported rigid bodies.The fluid flow is modelled by Lattice-Boltzmann Method,coupled to a set of ordinary differential equation...This work is concerned with the modelling of the interaction of fluid flow with flexibly supported rigid bodies.The fluid flow is modelled by Lattice-Boltzmann Method,coupled to a set of ordinary differential equations describing the dynamics of the solid body in terms its elastic and damping properties.The time discretization of the body dynamics is performed via the Time Discontinuous Galerkin Method.Several numerical examples are presented and highlight the robustness and efficiency of the proposed methodology,by means of comparisons with previously published results.The examples show that the present fluid-structure method is able to capture vortexinduced oscillations of flexibly-supported rigid body.展开更多
The onset of cavitating conditions inside the nozzle of liquid injectors is known to play a major role on spray characteristics,especially on jet penetration and break-up.In this work,we present a Direct Numerical Sim...The onset of cavitating conditions inside the nozzle of liquid injectors is known to play a major role on spray characteristics,especially on jet penetration and break-up.In this work,we present a Direct Numerical Simulation(DNS)based on the Lattice Boltzmann Method(LBM)to study the fluid dynamic field inside the nozzle of a cavitating injector.The formation of the cavitating region is determined via a multi-phase approach based on the Shan-Chen equation of state.The results obtained by the LBM simulation show satisfactory agreement with both numerical and experimental data.In addition,numerical evidence of bubble break-up,following upon flow-induced cavitation,is also reported.展开更多
An extension of the standard Shan-Chen model for non ideal-fluids,catering for mid-range,soft-core and hard-core repulsion,is investigated.It is shown that the inclusion of such mid-range interactions does not yield a...An extension of the standard Shan-Chen model for non ideal-fluids,catering for mid-range,soft-core and hard-core repulsion,is investigated.It is shown that the inclusion of such mid-range interactions does not yield any visible enhancement of the density jump across the dense and light phases.Such an enhancement can however be obtained by tuning the exponents of the effective interaction.The results also indicate that the inclusion of soft-core repulsion can prevent the coalescence of neighborhood bubbles,thereby opening the possibility of tailoring the size of multi-droplet configurations,such as sprays and related phase-separating fluids.展开更多
The simulation of multiphase flows is an outstanding challenge,due to the inherent complexity of the underlying physical phenomena and to the fact that multiphase flows are very diverse in nature,and so are the laws g...The simulation of multiphase flows is an outstanding challenge,due to the inherent complexity of the underlying physical phenomena and to the fact that multiphase flows are very diverse in nature,and so are the laws governing their dynamics.In the last two decades,a new class of mesoscopic methods,based on minimal lattice formulation of Boltzmann kinetic equation,has gained significant interest as an efficient alternative to continuum methods based on the discretisation of the NS equations for non ideal fluids.In this paper,three different multiphase models based on the lattice Boltzmann method(LBM)are discussed,in order to assess the capability of the method to deal with multiphase flows on a wide spectrum of operating conditions and multiphase phenomena.In particular,the range of application of each method is highlighted and its effectiveness is qualitatively assessed through comparison with numerical and experimental literature data.展开更多
基金G.F.acknowledges CINECA computational grant ISCRA-B IsB17–SPONGES,no.HP10B9ZOKQ and,partially,the support of PRIN projects CUP E82F16003010006(principal investigator,G.F.for the Tor Vergata Research Unit)and CUP E84I19001020006(principal investigator,G.Bella)support from the European Research Council under the Horizon 2020 Programme advanced grant agreement no.739964(‘COPMAT’)M.P.acknowledges the support of the National Science Foundation under grant no.CMMI 1901697.
文摘We detail some of the understudied aspects of the flow inside and around the Hexactinellid Sponge Euplectella aspergillum.By leveraging the flexibility of the Lattice Boltzmann Method,High Performance Computing simulations are performed to dissect the complex conditions corresponding to the actual environment at the bottom of the ocean,at depths between 100 and 1,000 m.These large-scale simulations unveil potential clues on the evolutionary adaptations of these deep-sea sponges in response to the surrounding fluid flow,and they open the path to future investigations at the interface between physics,engineering and biology.
文摘DSFD 2021,the 30th edition of the Discrete Simulation of Fluid Dynamics,took place again at University of Tuscia,Viterbo,Italy on September 13-172021.Due to the persisting uncertainties associated with the COVID-19 pandemics it was again organised virtually,like the preceding one.
文摘This work is concerned with the modelling of the interaction of fluid flow with flexibly supported rigid bodies.The fluid flow is modelled by Lattice-Boltzmann Method,coupled to a set of ordinary differential equations describing the dynamics of the solid body in terms its elastic and damping properties.The time discretization of the body dynamics is performed via the Time Discontinuous Galerkin Method.Several numerical examples are presented and highlight the robustness and efficiency of the proposed methodology,by means of comparisons with previously published results.The examples show that the present fluid-structure method is able to capture vortexinduced oscillations of flexibly-supported rigid body.
文摘The onset of cavitating conditions inside the nozzle of liquid injectors is known to play a major role on spray characteristics,especially on jet penetration and break-up.In this work,we present a Direct Numerical Simulation(DNS)based on the Lattice Boltzmann Method(LBM)to study the fluid dynamic field inside the nozzle of a cavitating injector.The formation of the cavitating region is determined via a multi-phase approach based on the Shan-Chen equation of state.The results obtained by the LBM simulation show satisfactory agreement with both numerical and experimental data.In addition,numerical evidence of bubble break-up,following upon flow-induced cavitation,is also reported.
文摘An extension of the standard Shan-Chen model for non ideal-fluids,catering for mid-range,soft-core and hard-core repulsion,is investigated.It is shown that the inclusion of such mid-range interactions does not yield any visible enhancement of the density jump across the dense and light phases.Such an enhancement can however be obtained by tuning the exponents of the effective interaction.The results also indicate that the inclusion of soft-core repulsion can prevent the coalescence of neighborhood bubbles,thereby opening the possibility of tailoring the size of multi-droplet configurations,such as sprays and related phase-separating fluids.
文摘The simulation of multiphase flows is an outstanding challenge,due to the inherent complexity of the underlying physical phenomena and to the fact that multiphase flows are very diverse in nature,and so are the laws governing their dynamics.In the last two decades,a new class of mesoscopic methods,based on minimal lattice formulation of Boltzmann kinetic equation,has gained significant interest as an efficient alternative to continuum methods based on the discretisation of the NS equations for non ideal fluids.In this paper,three different multiphase models based on the lattice Boltzmann method(LBM)are discussed,in order to assess the capability of the method to deal with multiphase flows on a wide spectrum of operating conditions and multiphase phenomena.In particular,the range of application of each method is highlighted and its effectiveness is qualitatively assessed through comparison with numerical and experimental literature data.
