Oil spill: are we doing enough to avoid it?

YesThis paper reviews the recent studies on the identification and cleaning methods, as well as the consequences of oil spill. The future progression on oil spill prevention studies are also projected here

Turbulence modelling of shallow water flows using Kolmogorov approach

YesThis study uses an improved k –ε coupled shallow water equations (SWE) model that equipped with the numerical computation of the velocity fluctuation terms to investigate the turbulence structures of the open channel flows. We adapted the Kolmogorov K41 scaling model into the k –ε equations to calculate the turbulence intensities and Reynolds stresses of the SWE model. The presented model was also numerically improved by a recently proposed surface gradient upwind method (SGUM) to allow better accuracy in simulating the combined source terms from both the SWE and k –ε equations as proven in the recent studies. The proposed model was first tested using the flows induced by multiple obstructions to investigate the utilised k –ε and SGUM approaches in the model. The laboratory experiments were also conducted under the non-uniform flow conditions, where the simulated velocities, total kinetic energies (TKE) and turbulence intensities by the proposed model were used to compare with the measurements under different flow non-uniformity conditions. Lastly, the proposed numerical simulation was compared with a standard Boussinesq model to investigate its capability to simulate the measured Reynolds stress. The comparison outcomes showed that the proposed Kolmogorov k –ε SWE model can capture the flow turbulence characteristics reasonably well in all the investigated flows.The Major State Basic Research Development Program (973 program) of China (No. 2013CB036402

Universal Velocity Distribution for Smooth and Rough Open Channel Flows

YesThe Prandtl second kind of secondary current occurs in any narrow channel flow causing velocity dip in the flow velocity distribution by introducing the anisotropic turbulence into the flow. Here, a study was conducted to explain the occurrence of the secondary current in the outer region of flow velocity distribution using a universal expression. Started from the basic Navier-Stokes equation, the velocity profile derivation was accomplished in a universal way for both smooth and rough open channel flows. However, the outcome of the derived theoretical equation shows that the smooth and rough bed flows give different boundary conditions due to the different formation of log law for smooth and rough bed cases in the inner region of velocity distribution. Detailed comparison with a wide range of different measurement results from literatures (from smooth, rough and field measured data) evidences the capability of the proposed law to represent flow under all bed roughness conditions

Numerical modelling of natural flood management and its associated microbial risks in the United Kingdom

YesThis paper reviews and discusses the recent studies of natural flood management (NFM) and its associated microbial risks in the UK and suggests set of numerical modelling approaches for their respective investigation. This study details the importance of precise numerical representation of the NFM to flood inundations and microbial risks caused by NFM measures. Possible future numerical advancements of the numerical modelling for the NFM and microbial activities are also discussed here

Environmental Hydraulics, Turbulence and Sediment Transport

YesIn the research on environmental hydraulics, its turbulence and sediment transport, constant challenges have been faced. The complexity of hydraulic impacts towards sediment morphology and turbulent flow properties makes research in this area a difficult task. However, due to pressure from climate change and the mounting issue of pollution, environmental flow studies are more crucial than ever. Bedforming within rivers is a complex process that can be influenced by the hydraulics, vegetated field, and various suspended and bedload transports. Changes in flow conditions due to rain and flood can further complicate a hydraulic system. To date, the turbulence, morphologic, and bedforming characteristics of natural environmental flows are still not well understood. This book aims to bring together a collection of state-of-the-art research and technologies to form a useful guide for the related research and engineering communities. It is useful for authorities and researchers interested in environmental and civil engineering studies, as well as for river and water engineers to understand the current state-of-the-art practices in environmental flow modelling, measurement and management. It is also a good resource for research, post-, or undergraduate students who wish to know about the most up-to-date knowledge in this field

Velocity Profile and Turbulence Structure Measurement Corrections for Sediment Transport-Induced Water-Worked Bed

YesWhen using point measurement for environmental or sediment laden flows, there is well-recognised risk for not having aligned measurements that causes misinterpretation of the measured velocity data. In reality, these kinds of mismeasurement mainly happen due to the misinterpretation of bed orientation caused by the complexity of its determination in natural flows, especially in bedload laden or rough bed flows. This study proposes a novel bed realignment method to improve the measured data benchmarking by three-dimensional (3D) bed profile orientation and implemented it into different sets of experimental data. More specifically, the effects of realignment on velocity profile and streamwise turbulence structure measurements were investigated. The proposed technique was tested against experimental data collected over a water-worked and an experimentally arranged well-packed beds. Different from the well-packed rough bed, the water-worked bed has been generated after long sediment transport and settling and hence can be used to verify the proposed bed-alignment technique thoroughly. During the flow analysis, the corrected velocity, turbulence intensity and Reynolds stress profiles were compared to the theoretical logarithmic law, exponential law and linear gravity (universal Reynolds stress distribution) profiles, respectively. It has been observed that the proposed method has improved the agreement of the measured velocity and turbulence structure data with their actual theoretical profiles, particularly in the near-bed region (where the ratio of the flow measurement vertical distance to the total water depth, z/h, is limited to ≤0.4)

Environmental Hydraulics, Turbulence and Sediment Transport

Ye

Assessing Student Attitudes Using a Computer-Aided Approach

YesIncluded in methods commonly used for assessing vocational training are oral assessments (OAs) since, in addition to assessing knowledge to a depth rarely achieved in other forms of testing, they give unique insight into students’ personal attitudes, which are important factors in the workplace. However, OAs require considerable preparation by the assessors, they can be restricted by time and assessor allocation, it is difficult to fully cover the course fairly, and they can put undue stress on the examinees, hence hindering a true expression of their skills and knowledge. OAs can give insight into a student’s personal attitudes, and the purpose here is to find the relationship between OA observed attitudes and those deduced from the computer-aided assessment. For the computer-aided assessments a scheme based on comparing two statements, followed by fuzzy AHP analysis, was used to determine the student’s attitude on such topics as general safety, work area tidiness and cleanliness, care and good use of hand tools and accuracy and testing of equipment. The results from the computer-aided approach were then compared with attitudes on the same topics obtained by oral assessment. For this work the important result was that there were strong correlations between the OA observed attitudes and the computer-aided assessment derived attitudes of the students. It also became clear however that for safety, the attitude of students (and perhaps workers) is more complicated than just having a ‘good’ or ‘bad’ attitude. Social pressure and organisational influence do seem to play a part so influencing or masking the student’s true attitudes. Satisfactory correlations were found between results of students’ attitudes when tested using the OA and computer-aided methods. Further work would need to be done to confirm generalization of substituting OA methods with a computer-aided assessment method

Experimental and Numerical Simulation of Sediment Flushing within Storage Tunnels

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Phenomenological features of turbulent hydrodynamics in sparsely vegetated open channel flow

YesThe present study investigates the turbulent hydrodynamics in an open channel flow with an emergent and sparse vegetation patch placed in the middle of the channel. The dimensions of the rigid vegetation patch are 81 cm long and 24 cm wide and it is prepared by a 7× 10 array of uniform acrylic cylinders by maintaining 9 cm and 4 cm spacing between centers of two consecutive cylinders along streamwise and lateral directions respectively. From the leading edge of the patch, the observed nature of time averaged flow velocities along streamwise, lateral and vertical directions is not consistent up to half length of the patch; however the velocity profiles develop a uniform behavior after that length. In the interior of the patch, the magnitude of vertical normal stress is small in comparison to the magnitudes of streamwise and lateral normal stresses. The magnitude of Reynolds shear stress profiles decreases with increasing downstream length from the leading edge of the vegetation patch and the trend continues even in the wake region downstream of the trailing edge. The increased magnitude of turbulent kinetic energy profiles is noticed from leading edge up to a certain length inside the patch; however its value decreases with further increasing downstream distance. A new mathematical model is proposed to predict time averaged streamwise velocity inside the sparse vegetation patch and the proposed model shows good agreement with the experimental data.Debasish Pal received financial assistance from SRIC Project of IIT Kharagpur (Project code: FVP