Mohammad Javad Ostad Mirza Tehrani

• Ph.D.
• Assistant Professor at K. N. Toosi University of Technology

In chute spillways, self-aeration occurs downstream of the inception point, where the turbulent boundary layer edge approaches the free surface, if they are long enough. Downstream of the inception point, a layer containing an air-water mixture extends gradually through the flow with the bulking effect. Flow bulking is essential in terms of sidewal...

Filtering spike contaminated velocity time series, recorded by Acoustic or Laser Doppler Velocimeter (ADV or LDV) in laboratory open-channel flow studies and field measurements, has always been challenging. Despite numerous conducted studies on the velocity time-series signal filtering methods, the importance of the number of spikes of invalid data...

Filtering spike contaminated velocity time series, recorded by Acoustic or Laser Doppler Velocimeter (ADV or LDV) in laboratory open-channel flow studies and field measurements, has always been challenging. Despite numerous conducted studies on the velocity time-series signal filtering methods, the importance of the number of spikes of invalid data...

Fluctuating bottom-pressures on stepped chutes are relevant for the spillway design. An abrupt slope reduction causes a local alteration of the bottom-pressure development. Little information is available regarding the air–water flow properties near an abrupt slope reduction on stepped chutes, particularly on the local pressure evolution. Neverthel...

Abrupt slope changes on stepped chutes may have a major effect on the hydraulics of skimming flows. The present study shows that the minimum discharge tested in the skimming flow regime leads to higher values of flow bulking depth (Y 99), bottom air concentration (C b), and mean (depth-averaged) air concentration (C mean). These observations are re...

In this study we developed a numerical model with the aid of Fluent Software to simulate the main characteristics of the flow i.e. free surface profile and scale-discharge relationship, over sharp crested weirs. The results showed that the numerical model is able to simulate the hydrodynamics of the complicated rapidly varied flow over sharp creste...

در طراحی و ساخت سرریزهای پلکانی، ممکن است به منظور تبعیت از توپوگرافی و جنس بستر و در نتیجه کاهش هزینه های ساخت نیاز به تغییر شیب ناگهانی باشد. از طرفی با تغییر شیب ناگهانی و افزایش فشار، هوای موجود در جریان به سمت سطح آزاد حرکت کرده (هوا زدائی) ودر نتیجه از غلظت هوای نزدیک به کف کاسته میشود. مقاله حاضر به بررسی تاثیر تغییر شیب ناگهانی بر غلظت هوای...

Several stepped spillways have been built in recent decades, mostly integrated in the downstream faces of roller compacted concrete dams. Among them, only a few have changing bottom slopes. Comprehensive information on the effect of a slope change on the flow features is lacking. This paper reports a systematic study of air entrainment and flow bul...

Numerous stepped spillways were built to date, namely on RCC gravity dams or on valley flanks besides embankment or rockfill dams, while some others are currently under design or construction. In some cases, slope changes may be required on stepped chutes, due to the topography, leading to reduced excavation and related economic benefits. A quite l...

Numerous stepped spillways were built during the last decades. In particular, a stepped spillway may be integrated economically into the downstream face of a RCC gravity dam, or on valley flanks besides embankment or rockfill dams, where slope changes may naturally be implemented due to topography and economic reasons. This paper presents and discu...

Flow characteristics on stepped spillways: The effect of abrupt slope change

Flow Characteristics On Stepped Spillways: The Effect of Abrupt Slope Changes

Aerators are constructed in high speed flows to prevent cavitation attack. Although horseshoe or circular tunnel sections can be converted to rectangular shape to use aerators similar to chute spillways, such a solution needs expensive subsequent concrete operation. Alternatively, annular aerators could be constructed which fit well with the tunnel...