Since the zero-net-mass-flux (ZNMF) jet was first used as a laboratory flow control method in 1990's, it has attracted much attention. The ZNMF jet has unique features such as compact actuator, no requirement for ...Since the zero-net-mass-flux (ZNMF) jet was first used as a laboratory flow control method in 1990's, it has attracted much attention. The ZNMF jet has unique features such as compact actuator, no requirement for external air supply, complex piping, etc., and becomes a hot topic research subject in fluid mechanics. This review introduces the state of the art in the development of ZNMF jet in the quiescent fluid, the interaction of the ZNMF jet with the cross flow and its application in the separation flow control. The evolution of the vortex ring/pair and the spacial flow structure of the ZNMF in quicent fluid or cross flow are presented, as well as the key parameter effects. At last, the applications of ZNMF jet in the wake control of the circular cylinder, the separation control on the airfoil and the aerodynamic force or moment control on MAV/UAV are presented.展开更多
With the advantages of biosafety and efficiency,increasing attention has been paid to the devices for gene and macromolecular drug delivery based on mechanoporation.The transient pore formation on the cell membrane al...With the advantages of biosafety and efficiency,increasing attention has been paid to the devices for gene and macromolecular drug delivery based on mechanoporation.The transient pore formation on the cell membrane allows cargo transportation when the membrane areal strain is beyond the critical pore value and below the lysis tension threshold.Based on this principle,we propose a method to apply the proper fluid stress on cells moving in a microchannel under the action of zero-net-mass-flux(ZNMF)jets.In this study,an immersed finite element method(IFEM)is adopted to simulate the interaction between the cells and the fluid fields so as to investigate the cell movement and deformation in this mechanoporation system.To evaluate the efficiency of the cargo delivery,a pore integral is defined as the mean pore rate when the cell passes through the jet region.By analyzing the effects of the parameters,including the pressure gradient along the microchannel,the jet amplitude,and the jet frequency,on the pore integrals,a group of optimized parameters for cargo delivery efficiency are obtained.Additionally,the stability and safety of this system are analyzed in detail.These results are helpful in designing the mechanoporation devices and improving their efficiency of drug delivery.展开更多
Volumetric particle image velocimetry(VPIV) refers to a PIV-based technique which can obtain full velocity components in a three-dimensional measurement volume.A new VPIV method with a single lens was developed.A thre...Volumetric particle image velocimetry(VPIV) refers to a PIV-based technique which can obtain full velocity components in a three-dimensional measurement volume.A new VPIV method with a single lens was developed.A three-vision prism was used to make viewing from different angles using one camera.The technique was tested and successfully applied to a three-dimensional three-component(3D3C) measurement of a zero-net-mass-flux jet flow.The accuracy of the measurement was investigated,specifically in steps of calibration,self-calibration and particle triangulation.Time sequence of a vortex ring development was presented.It was shown that the measurement has high accuracy with validation rate of velocity vector reaching about 95%.The flow with vortex ring passing the measurement volume was studied using both swirl strength and vorticity magnitude criteria.Through comparison,the swirl criterion was found to be superior to the criterion of vorticity in differentiating the rotation motion and the free shear.展开更多
基金the National Natural Science Foundation of China (Grant No. 10425207)the Aviation Creative Foundation of China (Grant No. 07A51001)
文摘Since the zero-net-mass-flux (ZNMF) jet was first used as a laboratory flow control method in 1990's, it has attracted much attention. The ZNMF jet has unique features such as compact actuator, no requirement for external air supply, complex piping, etc., and becomes a hot topic research subject in fluid mechanics. This review introduces the state of the art in the development of ZNMF jet in the quiescent fluid, the interaction of the ZNMF jet with the cross flow and its application in the separation flow control. The evolution of the vortex ring/pair and the spacial flow structure of the ZNMF in quicent fluid or cross flow are presented, as well as the key parameter effects. At last, the applications of ZNMF jet in the wake control of the circular cylinder, the separation control on the airfoil and the aerodynamic force or moment control on MAV/UAV are presented.
基金supported by the National Natural Science Foundation of China(Nos.11832017 and 12172209)the Key Research Project of Zhejiang Laboratory of China(No.2021PE0AC02)。
文摘With the advantages of biosafety and efficiency,increasing attention has been paid to the devices for gene and macromolecular drug delivery based on mechanoporation.The transient pore formation on the cell membrane allows cargo transportation when the membrane areal strain is beyond the critical pore value and below the lysis tension threshold.Based on this principle,we propose a method to apply the proper fluid stress on cells moving in a microchannel under the action of zero-net-mass-flux(ZNMF)jets.In this study,an immersed finite element method(IFEM)is adopted to simulate the interaction between the cells and the fluid fields so as to investigate the cell movement and deformation in this mechanoporation system.To evaluate the efficiency of the cargo delivery,a pore integral is defined as the mean pore rate when the cell passes through the jet region.By analyzing the effects of the parameters,including the pressure gradient along the microchannel,the jet amplitude,and the jet frequency,on the pore integrals,a group of optimized parameters for cargo delivery efficiency are obtained.Additionally,the stability and safety of this system are analyzed in detail.These results are helpful in designing the mechanoporation devices and improving their efficiency of drug delivery.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11102013,10832001)the "Weishi" Foundation of Beijing University of Aeronautics and Astronautics (Grant No. YWF-12-RHRS-008)
文摘Volumetric particle image velocimetry(VPIV) refers to a PIV-based technique which can obtain full velocity components in a three-dimensional measurement volume.A new VPIV method with a single lens was developed.A three-vision prism was used to make viewing from different angles using one camera.The technique was tested and successfully applied to a three-dimensional three-component(3D3C) measurement of a zero-net-mass-flux jet flow.The accuracy of the measurement was investigated,specifically in steps of calibration,self-calibration and particle triangulation.Time sequence of a vortex ring development was presented.It was shown that the measurement has high accuracy with validation rate of velocity vector reaching about 95%.The flow with vortex ring passing the measurement volume was studied using both swirl strength and vorticity magnitude criteria.Through comparison,the swirl criterion was found to be superior to the criterion of vorticity in differentiating the rotation motion and the free shear.
