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Sriram Venkatachalam
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Sriram Venkatachalam
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Sriram Venkatachalam
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Sriram, V.
Sriram, Venkatachalam
Venkatachalam, Sriram
V, Sriram
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5 results
Now showing 1 - 5 of 5
- PublicationFlow-structure interference effects with the surrounding structure in the choked quasi-steady condition of tsunami: Comparison with traditional obstruction approach(01-09-2022)
;Harish, S.; ;Schüttrumpf, HolgerTo understand tsunami flow interaction with the structure occupying a certain percentage of flow channel width in the field, several authors modelled experiments or numerical simulations with the single structure occupying the same obstruction ratio, denoted by b/W (b = single structure width; W = flow channel width, considered as flume width). This setup resulted from laboratory width constraints or computational time reduction in numerical modelling, leading to the inherent assumption of symmetrical flow conditions at the flume walls. In this study, we compare the flow and force characteristics of the b/W setup with the results from the unsteady flow-structure interaction experiments conducted along with the adjacent structures in the flow choked condition, thereby replicating a realistic flow behaviour (termed as b/W* setup, here W* represents the actual flow width replicating the real field). The results from the experiments indicate that the change in the bore height at the structure front (h*f) is marginal or almost negligible between the two setups, independent of Fr. However, the bore height at the structure backside (h*r) is significantly altered. The existence of the hydrostatic pressure at the structure front and backside still ensured F*≈ρbg(hf*2−hr*2)/2 in flow-choked condition for the b/W* setup. Further, the 'h*f' prediction using the conservation of mass and momentum equations is improved. In regards to the vertical uplift force (F*u), the ratio of F*u/F*ub (F*ub = buoyancy force calculated using the average of h*f and h*r in the b/W* setup) is found to be approximately 1.15 times higher than Fu/Fub in the b/W setup (Harish et al., 2022a). - PublicationExperimental investigation of floating debris impact loading on structures during extreme waves like tsunami(01-01-2018)
;Harish, S.; ; ; Didenkulova, I.Debris generated during extreme events like the tsunami can impose substantial impact loading on structures closer in the coastal zone. Majority of design codes do not quantify the impact forces close to reality owing to uncertainties in defining the wave characteristics and a lack of knowledge in understanding the underlying physical processes. The present study focuses on the measurement of forces which a coastal structure would encounter due to the impact of debris in motion during such an extreme event. The study herein focuses the motion of the debris due to undular bores. 1:20 scaled model of structure and the debris were used. Experiments were conducted in a wave flume 72.5 m long and 2 m wide. A beach slope of 1:30 is laid to replicate the coastal zone. By varying the wave heights and time periods, different types of waves such as elongated single pulse waves, symmetrical N waves and unsymmetrical N waves were generated replicating the characteristics of a tsunami as close as possible. The impact tests were conducted using box shaped smart devices as debris of weight 4.62 kg, 5.82 kg and 7.02 kg. The debris is attached with an accelerometer for measuring the impact acceleration. In order to have a better understanding of the behavior of debris during the impact, a camera at a speed of 120 fps is operated. The force acting on the structure is measured with a load cell. The forces due to the velocity of the debris and the mass is compared with the force measured using load cell. The details of the testing facility, model parameters, test set-up, test procedure, analysis of results and discussion are presented in the paper. - PublicationOn the generation of tsunami in a large scale wave flume(01-01-2014)
;Schimmels, S.; ;Didenkulova, I.Fernández, H.This paper presents very long, i.e. real tsunami-like wave generation in a large scale wave flume using a piston type wave maker. Waves of periods between 30 s and more than 100 s were generated at 1 m water depth using two different approaches: (i) deriving the wave board motion directly by integration of the water surface elevation, composed of a different number of solitons (sech2 waves) and (ii) using an iterative self correcting method (SCM). The importance of very long wave generation instead of solitary waves and the necessity for long testing facilities is discussed and results from GWK experiments are presented for single pulses (elongated solitons), N-waves and real tsunami records, either approximated as a combination of solitons or applying the SCM to the time series directly. - PublicationTsunami generation in a large scale experimental facility(01-04-2016)
;Schimmels, Stefan; Didenkulova, IraExperimental studies on tsunami are carried out since many years, most of them by generating solitary waves with a piston type wave maker. However, today it is more and more appreciated that these kinds of waves actually do not represent a real tsunami very well, as particularly for the shallow waters at the coast the wave length becomes comparably far too short. Recently new generation methods for scaled down real tsunami experiments were suggested, as it was doubted that sufficiently long waves could be generated with a classical wave maker. The present paper shall disprove these arguments by providing results of a study carried out in the Large Wave Flume (Großer Wellenkanal, GWK), where waves of periods between 30s and more than 100s at 1m water depth were successfully generated with a piston type wave maker. Results for elongated solitary waves, trough led N-waves and real tsunami records as a combination of a different number of general solitons (sech2 waves) are presented. Finally, the requirements and limitations to bring a "real" tsunami into the laboratory are discussed. - PublicationEffect of the buffer blocks in attenuating a tsunami-like flow(15-10-2023)
;Percy, V. P.Golda; ; Schüttrumpf, HolgerThe construction of protective structures along the coast constitutes a crucial component of tsunami mitigation measures. Most commonly adopted tsunami mitigation measures are submerged structures, elevating the crest level of existing coastal defence structures, or soft measures. However, less considered measures to reduce the inundation level are a well-planned group of buffer blocks, which could not only act as a mitigation measure but also can serve as a facility along the shore to sit and relax during normal conditions. The buffer blocks can be constructed without affecting the scenic beauty. This paper presents the influence of the buffer block characteristics in attenuating the flow depth, and flow velocity. To carry out the study, the numerical model, OpenFOAM is adopted to simulate the dam break setup generating tsunami-like flow. The reduction in the flow velocity is governed by its the configuration. It was observed that a single-row configuration can reduce the momentum flux to an extent of 5–40%. Further, the results indicate that an increase in the number of rows in staggered configurations might enhance the percentage reduction in the flow characteristics. In addition, the forces on the buffer blocks for various configurations are computed and analysed from the existing literature.