Rayleigh-Taylor instability in a thermocline based thermal storage tank

Numerical simulations are performed to study the stability characteristics of a molten salt thermocline storage unit. Perturbations are introduced into a stable flow field in such a way as to make the top-fluid heavier than the fluid at the bottom, thereby causing a possible instability in the system. The evolution pattern of the various disturbances are examined in detail. Disturbances applied for short duration get decayed before they could reach the thermocline, whereas medium and long duration disturbances evolve into a ``falling spike'' or ``stalactite-like'' structure and destabilize the thermocline. Rayleigh Taylor instability is observed inside the storage tank. The effect of the duration, velocity and temperature of the disturbance on thermocline thickness and penetration length are studied. A quadratic time dependence of penetration length was observed. New perspectives on thermocline breakdown phenomena are obtained from the numerical flow field. (C) 2015 Elsevier Masson SAS. All rights reserved.

Simulation of Free-Surface Flow in a Tank Using the Navier-Stokes Model and Unstructured Finite Volume Method

Modelling free-surface flow has very important applications in many engineering areas such as oil transportation and offshore structures. Current research focuses on the modelling of free surface flow in a tank by solving the Navier-Stokes equation. An unstructured finite volume method is used to discretize the governing equations. The free surface is tracked by dynamically adapting the mesh and making it always surface conforming. A mesh-smoothing scheme based on the spring analogy is also implemented to ensure mesh quality throughout the computaiton. Studies are performed on the sloshing response of a liquid in an elastic container subjected to various excitation frequencies. Further investigations are also carried out on the critical frequency that leads to large deformation of the tank walls. Another numerical simulation involves the free-surface flow past as submerged obstacle placed in the tank to show the flow separation and vortices. All these cases demonstrate the capability of this numerical method in modelling complicated practical problems.

Sediment incipience in turbulence generated in a square tank by a vertically oscillating grid

The failure of hydraulic structures in many estuaries and coastal regions around the world has been attributed to sediment transport and local scour. The sediment incipience in homogenous turbulence generated by oscillating grid is studied in this paper. The turbulent flow is measured by particle tracer velocimetry (PTV) technique. The integral length scale and time scale of turbulence are obtained. The turbulent flow near the wall is measured by local optical magnification. The sediment incipience is described by static theory. The relationship of probability of sediment incipience and the turbulent kinetic energy were obtained experimentally and theoretically. The distribution of the turbulent kinetic energy near the wall is found to obey the power law and the turbulent energy is further identified as the dynamic mechanism of sediment incipience.

The Think Tank Making Lifelong Learning a reality

This publication captures the outputs of an event organised by JISC infoNet, the Association for Learning Technology (ALT) and the JISC, held in February 2005 at the Orange Studio in Birmingham. The event was entitled ‘IT Won’t Work Here’ and it aimed to explore what is required to make Lifelong Learning a reality. The title was a play on words indicating both the need to overcome a range of negative attitudes and for the ALT and JISC communities to focus on more than simply the technology required to support learners moving across the different education sectors.

Outputs from the Manchester Metropolitan University distance learning think tank event

An overview of, and the emergent themes from, the Manchester Metropolitan University distance learning think tank event which took place on 10th July 2014 and aimed to provide a forum to explore and discuss some of the key issues for colleagues across the university involved in planning, setting-up and delivering such programmes at MMU.

Poster: Outputs from the Manchester Metropolitan University online distance learning think tank event

Poster from the overview of, and the emergent themes from, the Manchester Metropolitan University distance learning think tank event which took place on 10th July 2014 and aimed to provide a forum to explore and discuss some of the key issues for colleagues across the university involved in planning, setting-up and delivering such programmes at MMU.

Commercial production of Clarias fry and fingerlings in indoor and outdoor concrete tank systems

Induced breeding technique by hypophysation is being applied at the Kainji Lake Research Institute Fisheries Division Hatchery complex in New Bussa, Nigeria, for the production of Clarias fry and fingerlings in indoor and outdoor concrete tank systems. The hatchlings are fed on livefood (zooplankton) and artificial feed. Source of zooplankton is from cultured stock which is maintained throughout the breeding season by fertilization. Production values show that an average of over 4,000 hatchlings (larvae) can be produced by a female breeder (over-700g wt) and percentage survival after two months ranges between 70 to 75%. With the proposed modification and expansion project, an estimated production of over 0.5 million fingerlings per breeding season is projected

The variation of water quality in the outdoor concrete tank and earthen pond

The paper reports on the study carried out at the Federal College of Freshwater Fisheries and Technology (Nigeria) and the Hatchery Complex in 1997. The physico-chemical parameters of an earthen fish pond and concrete tank were analysed. The abundance and distribution of phytoplankton and zooplankton were recorded. A total of eight species of phytoplankton were observed. These species can be classified as Chlorophyceae (green algae), Bacillariophyceae (diatom algae) and Cyanophyta (blue-green algae). Eight zooplankton species were observed in the pond and 6 in the tank. Moina was observed and recorded as the most abundant cladoceran species in the tank

Culture feasibility of african catfish (Clarias gariepinus Lin.) fry in glass tank and synthetic hapa system using supplemental diets

An experiment was carried out with 1 0 days old Clarias gariepinus fry over a period of 42 days to determine the effects of different feeds on growth and survival of African catfish fry in glass tanks. The experiment was designed into four treatments each having three replications. Thus treatment 1 (T1) was named as Tank Tubifex (TT) and treatment 2 (T2) as Tank Sabinco (TS), treatment 3 as Pond Tubifex (PT), and treatment 4 (T4) as Pond Sabinco (PS). Live Tubifex (protein levels 64.48%) was supplied to treatments 1 and 3 and rest of the treatments were supplied Sabinco starter-1 (protein levels 40.13%). The highest and the lowest growth in total length and weight were 12.90cm, 18.77g and 6.17cm, 4.04g recorded from the treatments 3 and 2, respectively. Growth of catfish fry under treatment 3 in terms of both length and weight were significantly higher (P<0.01) than those of the other treatments. However treatment 2 showed the significantly lowest (P<0.01) growth performance among the various treatments. The highest survival rate (92%) was also obtained with treatment 3. Tubifex proved to be the best larval feed in respect of growth and survival rate.