Research on scale effects on flows over weirs has been conducted on a limited basis, primarily focusing on flows upstream of a single-type weir, such as ogee, broad-crested, and sharp-crested (linear and non-linear) w...Research on scale effects on flows over weirs has been conducted on a limited basis, primarily focusing on flows upstream of a single-type weir, such as ogee, broad-crested, and sharp-crested (linear and non-linear) weirs. However, the scale effects downstream of these single-type weirs have not been thoroughly investigated. This study examined the scale effects on flows over a combined weir system consisting of an ogee weir and a sharp-crested weir, both upstream and downstream, utilizing physical modeling at a 1:33.33 scale based on Froude similarity and three-dimensional (3D) computational fluid dynamics (CFD) modeling. The sharp-crested weir in this study was represented by two sluice gates that remain closed and submerged during flood events. The experimental data confirmed that the equivalent discharge coefficients of the combined weir system behaved similarly to those of a sharp-crested weir across various H/P (where H is the total head, and P is the weir height) values. However, scale effects on the discharge rating curve due to surface tension and viscosity could only be minimized when H/P > 0.4, Re > 26 959, and We > 240 (where Re and We are the Reynolds and Weber numbers, respectively), provided that the water depth exceeded 0.042 m above the crest. Additionally, Re greater than 4 × 104 was necessary to minimize scale effects caused by viscosity in flows in the spillway channel and stilling basin (with baffle blocks). The limiting criteria aligned closely with existing literature. This study offers valuable insights for practical applications in hydraulic engineering in the future.展开更多
The major object of this research is the numerical analysis of flow fields over ogee spillway with elliptical crest and the USBR （United States Bureau of Reclamation） in both vertical upstream face state and incline...The major object of this research is the numerical analysis of flow fields over ogee spillway with elliptical crest and the USBR （United States Bureau of Reclamation） in both vertical upstream face state and inclined one with slope 3H：3V. And it also researched the effect of geometry, slopes of curvature of spillway upstream face and water head on the flow field and pressure distribution. In fact Navier-Stokes was used for analyzing flow fields, and VOF （volume of fluid） method was utilized for assigning the free surface, k-e turbulence model RNG was used for analyzing the turbulence field too. Studies show the geometric changes of the spillway pressure distribution and discharge. The spillway with the elliptical crest due to existence of coherence at the curvature of crest created less negative pressure on the crest than USBR crest. So it increased efficiency of spillway discharge about 2% than USBR spillway. Inclining upstream face of spillway affects discharge coefficients and discharge. Hence slope 3H：3V in the upstream face of the crest causes 3.4% more negative pressure in tangent surface and discharges more 1.62% discharge than one of spillway including vertical face. Effect of water head on pressure distribution is simulated on both spillways with elliptical and USBR crest. Numerical results compared to experimental data are satisfactory. The resulted errors of computed discharge compared with experimental data were 0.83%-2% in USBR spillway and 0.29%-2.87% in the elliptical spillway.展开更多
Aim:Traditional facelift techniques rely on pulling.They approach the superficial or intermediate layers where the facial nerves and muscles are located,increasing the risk of facial nerve injury.They approach the cen...Aim:Traditional facelift techniques rely on pulling.They approach the superficial or intermediate layers where the facial nerves and muscles are located,increasing the risk of facial nerve injury.They approach the central oval from the periphery and produce unnatural vectors of pull and aesthetic results.Alternative techniques that work on the subperiosteal plane using endoscopic techniques are described.Modern concepts of volume augmentation,beautification and rejuvenation of the facial expression are an inherent part of such techniques,or can be easily integrated.Methods:The central oval is approached via four small scalp incisions and additional intraoral,upper gingivo-buccal incisions.The interconnected frontal subperiosteal,temporal subfascial and midface subperiosteal areas are lifted,imbricated and suspended sequentially.The brow/forehead is suspended to the skull using cortical screws.The midface and lower periorbita are suspended to the fascia of the temporal muscle.The buccal fat pad is used to enhance the ogee line of the midface.Other three-dimensional volumetric maneuvers can easily be applied.In this setting,upper and lower lid blepharoplasties become more straightforward,skin only procedures.Actinic or nicotine damaged skin can be treated with lasers,peels or fluidified fat grafting in the same setting.The excess skin on the lower face and neck can be redrapped with standard cervicofacial techniques.Deep subplatysmal cervicoplasty can be done concomitantly,or at another time to complete comprehensive rejuvenation.Results:The procedures described herein has been performed in 824 patients with excellent aesthetic results and low complication rate.The average rate of rejuvenation was 18 years. ;Conclusion:These combination techniques are called Biplanar Endoscopic Assisted Mask and Triplanar Endoscopic Assisted Mask facial rejuvenation.They are advanced techniques of facial rejuvenation that provide comprehensive,natural,long lasting results.展开更多
基金supported by the Ministry of Public Works and Housing of Indonesia and Parahyangan Catholic University(Grant No.II/PD/2023-07/02-SJ).
文摘Research on scale effects on flows over weirs has been conducted on a limited basis, primarily focusing on flows upstream of a single-type weir, such as ogee, broad-crested, and sharp-crested (linear and non-linear) weirs. However, the scale effects downstream of these single-type weirs have not been thoroughly investigated. This study examined the scale effects on flows over a combined weir system consisting of an ogee weir and a sharp-crested weir, both upstream and downstream, utilizing physical modeling at a 1:33.33 scale based on Froude similarity and three-dimensional (3D) computational fluid dynamics (CFD) modeling. The sharp-crested weir in this study was represented by two sluice gates that remain closed and submerged during flood events. The experimental data confirmed that the equivalent discharge coefficients of the combined weir system behaved similarly to those of a sharp-crested weir across various H/P (where H is the total head, and P is the weir height) values. However, scale effects on the discharge rating curve due to surface tension and viscosity could only be minimized when H/P > 0.4, Re > 26 959, and We > 240 (where Re and We are the Reynolds and Weber numbers, respectively), provided that the water depth exceeded 0.042 m above the crest. Additionally, Re greater than 4 × 104 was necessary to minimize scale effects caused by viscosity in flows in the spillway channel and stilling basin (with baffle blocks). The limiting criteria aligned closely with existing literature. This study offers valuable insights for practical applications in hydraulic engineering in the future.
文摘The major object of this research is the numerical analysis of flow fields over ogee spillway with elliptical crest and the USBR （United States Bureau of Reclamation） in both vertical upstream face state and inclined one with slope 3H：3V. And it also researched the effect of geometry, slopes of curvature of spillway upstream face and water head on the flow field and pressure distribution. In fact Navier-Stokes was used for analyzing flow fields, and VOF （volume of fluid） method was utilized for assigning the free surface, k-e turbulence model RNG was used for analyzing the turbulence field too. Studies show the geometric changes of the spillway pressure distribution and discharge. The spillway with the elliptical crest due to existence of coherence at the curvature of crest created less negative pressure on the crest than USBR crest. So it increased efficiency of spillway discharge about 2% than USBR spillway. Inclining upstream face of spillway affects discharge coefficients and discharge. Hence slope 3H：3V in the upstream face of the crest causes 3.4% more negative pressure in tangent surface and discharges more 1.62% discharge than one of spillway including vertical face. Effect of water head on pressure distribution is simulated on both spillways with elliptical and USBR crest. Numerical results compared to experimental data are satisfactory. The resulted errors of computed discharge compared with experimental data were 0.83%-2% in USBR spillway and 0.29%-2.87% in the elliptical spillway.
文摘Aim:Traditional facelift techniques rely on pulling.They approach the superficial or intermediate layers where the facial nerves and muscles are located,increasing the risk of facial nerve injury.They approach the central oval from the periphery and produce unnatural vectors of pull and aesthetic results.Alternative techniques that work on the subperiosteal plane using endoscopic techniques are described.Modern concepts of volume augmentation,beautification and rejuvenation of the facial expression are an inherent part of such techniques,or can be easily integrated.Methods:The central oval is approached via four small scalp incisions and additional intraoral,upper gingivo-buccal incisions.The interconnected frontal subperiosteal,temporal subfascial and midface subperiosteal areas are lifted,imbricated and suspended sequentially.The brow/forehead is suspended to the skull using cortical screws.The midface and lower periorbita are suspended to the fascia of the temporal muscle.The buccal fat pad is used to enhance the ogee line of the midface.Other three-dimensional volumetric maneuvers can easily be applied.In this setting,upper and lower lid blepharoplasties become more straightforward,skin only procedures.Actinic or nicotine damaged skin can be treated with lasers,peels or fluidified fat grafting in the same setting.The excess skin on the lower face and neck can be redrapped with standard cervicofacial techniques.Deep subplatysmal cervicoplasty can be done concomitantly,or at another time to complete comprehensive rejuvenation.Results:The procedures described herein has been performed in 824 patients with excellent aesthetic results and low complication rate.The average rate of rejuvenation was 18 years. ;Conclusion:These combination techniques are called Biplanar Endoscopic Assisted Mask and Triplanar Endoscopic Assisted Mask facial rejuvenation.They are advanced techniques of facial rejuvenation that provide comprehensive,natural,long lasting results.
