Deformation in the Zagros suture zone is a result of the oblique collision of the AfroArabian continent with the Central Iranian microcontinents.Various types of folding and faulting are characteristic features of the...Deformation in the Zagros suture zone is a result of the oblique collision of the AfroArabian continent with the Central Iranian microcontinents.Various types of folding and faulting are characteristic features of the study area and indicate the performance of a high strain tectonic regime in this region.To distinguish deformation geometry during the collisional events,strain measurements have been carried out,using the R_(f)/φ method on deformed radiolarian microfossils,in the Zagros suture zone.Based on the results,the strain ellipsoid shape is in the range of general flattening to plane strain(K=0.16 – 1.12).Measured mean kinematic vorticity number(W_(m)) in the deformed radiolarian rocks ranges between 0.50 and 0.87,which implies that exhumation of the Abade-Tashk area was facilitated by a general shear flow(35%<simple shear<65% and 45%<pure shear<65%).Kinematic vorticity numbers,the amounts of Octahedral shear strain,the ellipsoid eccentricity,and strain ratios systematically increasing towards the thrust fault.The study of deformation in the study area shows that the Zagros suture zone can be considered as a transpressional zone.展开更多
Large Eddy Simulation （LES） was coupled with a mass transfer cavitation model to predict unsteady 3-D turbulent cavita- ting flows around a twisted hydrofoil. The wall-adapting local eddy-viscosity （WALE） model wa...Large Eddy Simulation （LES） was coupled with a mass transfer cavitation model to predict unsteady 3-D turbulent cavita- ting flows around a twisted hydrofoil. The wall-adapting local eddy-viscosity （WALE） model was used to give the Sub-Grid Scale （SGS） stress term. The predicted 3-D cavitation evolutions, including the cavity growth, break-off and collapse downstream, and the shedding cycle as well as its frequency agree fairly well with experimental results. The mechanism for the interactions between the cavitation and the vortices was discussed based on the analysis of the vorticity transport equation related to the vortex stretching, volumetric expansion/contraction and baroclinic torque terms along the hydrofoil mid-plane. The vortical flow analysis demonstrates that cavitation promotes the vortex production and the flow unsteadiness. In non-cavitation conditions, the streamline smoothly passes along the upper wall of the hydrofoil with no boundary layer separation and the boundary layer is thin and attached to the foil except at the trailing edge. With decreasing cavitation number, the present case has O＂ = 1.07, and the attached sheet cavitation beco- mes highly unsteady, with periodic growth and break-off to form the cavitation cloud. The expansion due to cavitation induces boun- dary layer separation and significantly increases the vorticity magnitude at the cavity interface. A detailed analysis using the vorticity transport equation shows that the cavitation accelerates the vortex stretching and dilatation and increases the baroclinic torque as the major source of vorticity generation. Examination of the flow field shows that the vortex dilatation and baroclinic torque terms in- crease in the cavitating case to the same magnitude as the vortex stretching term, while for the non-cavitating case these two terms are zero.展开更多
The vorticity analysis technique was applied to measure the different lithological units,such as schist,metagranite and metavolcano-sedimentary rocks,which are present in the Halaban region.This work aims to interpret...The vorticity analysis technique was applied to measure the different lithological units,such as schist,metagranite and metavolcano-sedimentary rocks,which are present in the Halaban region.This work aims to interpret the relationship between the different lithologies and the tectonic setting,in order to elucidate the nature of kinematic analysis in the Halaban region.The kinematic analyses were applied to feldspar porphyroclasts,quartz and hornblende for twenty-six samples.The kinematic vorticity number(Wm)for deformed rocks in the study area ranged from~0.6 to 0.9.The direction of the long axes for finite strain data(X axes)revealed a WNW trend with shallow dipping.The direction of the short axes for finite strain data(Z axes)were represented by vertical with associated horizontal foliation.The results of the kinematic vorticity and strain analyses are characterized by simple shear with different degrees of deformation in the Halaban region.Furthermore,our finite strain data shows no significant volume change during deformation.The subhorizontal foliation was synchronized with thrusting and deformation.Furthermore,throughout the overlying nappes,the same attitudes of tectonic contacts are observable,the nappes in the orogens being formed from simple shear deformation.展开更多
This paper summarizes the recent development of a portable self-contained system to unravel the intricate multiscale dynamical processes from real oceanic flows, which are in nature highly nonlinear and intermittent i...This paper summarizes the recent development of a portable self-contained system to unravel the intricate multiscale dynamical processes from real oceanic flows, which are in nature highly nonlinear and intermittent in space and time. Of particular focus are the interactions among largescale, mesoscale, and submesoscale processes.We firsu introduce the concept of scale window, and an orthogonal subspace decomposition technigue called multiscale window transform (MWT). Established on MWT is a rigorous formalism of multiscale transport, perfect transfer, and multiscale conversion, which makes a new methodology, multiscale energy and vorticity analysis (MS-EVA). A direct application of the MS-EVA is the development of a novel localized instability analysis, generalizing the classical notion of hydrodynamic instability to finite amplitude processes on irregularly variable domains. The theory is consistent with the analytical solutions of Eady's model and Kuo's model, the benchmark models of baroclinic instability and barotropic instability; it is further validated with a vortex shedding control problem. We have put it to application with a variety of complicated real ocean problems, which would be otherwise very difficult, if not impossible, to tackle. Briefly shown in this paper include the dynamical studies of a highly variable open ocean front, and a complex coastal ocean circulation. In the former, it is found that underlying the frontal meandering is a convective instability followed by an absolute instability, and correspondingly a rapid spatially amplifying mode locked into a temporally growing mode; in the latter, we see a real ocean example of how upwelling can be driven by winds through nonlinear instability, and how winds may excite the ocean via an avenue which is distinctly different from the classical paradigms. This system is mathematically rigorous, physically robust, and practically straightforward.展开更多
文摘Deformation in the Zagros suture zone is a result of the oblique collision of the AfroArabian continent with the Central Iranian microcontinents.Various types of folding and faulting are characteristic features of the study area and indicate the performance of a high strain tectonic regime in this region.To distinguish deformation geometry during the collisional events,strain measurements have been carried out,using the R_(f)/φ method on deformed radiolarian microfossils,in the Zagros suture zone.Based on the results,the strain ellipsoid shape is in the range of general flattening to plane strain(K=0.16 – 1.12).Measured mean kinematic vorticity number(W_(m)) in the deformed radiolarian rocks ranges between 0.50 and 0.87,which implies that exhumation of the Abade-Tashk area was facilitated by a general shear flow(35%<simple shear<65% and 45%<pure shear<65%).Kinematic vorticity numbers,the amounts of Octahedral shear strain,the ellipsoid eccentricity,and strain ratios systematically increasing towards the thrust fault.The study of deformation in the study area shows that the Zagros suture zone can be considered as a transpressional zone.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 51206087, 51179091)the Major National Scientific Instrument and Equipment Development Project (Grant No. 2011YQ07004901)the China Postdoctoral Science Foundation (Grant Nos. 2011M500314,2012T50090)
文摘Large Eddy Simulation （LES） was coupled with a mass transfer cavitation model to predict unsteady 3-D turbulent cavita- ting flows around a twisted hydrofoil. The wall-adapting local eddy-viscosity （WALE） model was used to give the Sub-Grid Scale （SGS） stress term. The predicted 3-D cavitation evolutions, including the cavity growth, break-off and collapse downstream, and the shedding cycle as well as its frequency agree fairly well with experimental results. The mechanism for the interactions between the cavitation and the vortices was discussed based on the analysis of the vorticity transport equation related to the vortex stretching, volumetric expansion/contraction and baroclinic torque terms along the hydrofoil mid-plane. The vortical flow analysis demonstrates that cavitation promotes the vortex production and the flow unsteadiness. In non-cavitation conditions, the streamline smoothly passes along the upper wall of the hydrofoil with no boundary layer separation and the boundary layer is thin and attached to the foil except at the trailing edge. With decreasing cavitation number, the present case has O＂ = 1.07, and the attached sheet cavitation beco- mes highly unsteady, with periodic growth and break-off to form the cavitation cloud. The expansion due to cavitation induces boun- dary layer separation and significantly increases the vorticity magnitude at the cavity interface. A detailed analysis using the vorticity transport equation shows that the cavitation accelerates the vortex stretching and dilatation and increases the baroclinic torque as the major source of vorticity generation. Examination of the flow field shows that the vortex dilatation and baroclinic torque terms in- crease in the cavitating case to the same magnitude as the vortex stretching term, while for the non-cavitating case these two terms are zero.
基金The authors would like to extend their sincere appreciation to the Deanship of Scientific Research at King Saud University for its funding of this research through Research Group Project No.RG-1440-011.
文摘The vorticity analysis technique was applied to measure the different lithological units,such as schist,metagranite and metavolcano-sedimentary rocks,which are present in the Halaban region.This work aims to interpret the relationship between the different lithologies and the tectonic setting,in order to elucidate the nature of kinematic analysis in the Halaban region.The kinematic analyses were applied to feldspar porphyroclasts,quartz and hornblende for twenty-six samples.The kinematic vorticity number(Wm)for deformed rocks in the study area ranged from~0.6 to 0.9.The direction of the long axes for finite strain data(X axes)revealed a WNW trend with shallow dipping.The direction of the short axes for finite strain data(Z axes)were represented by vertical with associated horizontal foliation.The results of the kinematic vorticity and strain analyses are characterized by simple shear with different degrees of deformation in the Halaban region.Furthermore,our finite strain data shows no significant volume change during deformation.The subhorizontal foliation was synchronized with thrusting and deformation.Furthermore,throughout the overlying nappes,the same attitudes of tectonic contacts are observable,the nappes in the orogens being formed from simple shear deformation.
文摘This paper summarizes the recent development of a portable self-contained system to unravel the intricate multiscale dynamical processes from real oceanic flows, which are in nature highly nonlinear and intermittent in space and time. Of particular focus are the interactions among largescale, mesoscale, and submesoscale processes.We firsu introduce the concept of scale window, and an orthogonal subspace decomposition technigue called multiscale window transform (MWT). Established on MWT is a rigorous formalism of multiscale transport, perfect transfer, and multiscale conversion, which makes a new methodology, multiscale energy and vorticity analysis (MS-EVA). A direct application of the MS-EVA is the development of a novel localized instability analysis, generalizing the classical notion of hydrodynamic instability to finite amplitude processes on irregularly variable domains. The theory is consistent with the analytical solutions of Eady's model and Kuo's model, the benchmark models of baroclinic instability and barotropic instability; it is further validated with a vortex shedding control problem. We have put it to application with a variety of complicated real ocean problems, which would be otherwise very difficult, if not impossible, to tackle. Briefly shown in this paper include the dynamical studies of a highly variable open ocean front, and a complex coastal ocean circulation. In the former, it is found that underlying the frontal meandering is a convective instability followed by an absolute instability, and correspondingly a rapid spatially amplifying mode locked into a temporally growing mode; in the latter, we see a real ocean example of how upwelling can be driven by winds through nonlinear instability, and how winds may excite the ocean via an avenue which is distinctly different from the classical paradigms. This system is mathematically rigorous, physically robust, and practically straightforward.
