The behaviour of warm water discharge at a temperature \(T_{m}\) horizontally into a homogeneous body of cold fresh water at a temperature \(T=0\) was investigated by means of a numerical model through lock-exchange. Water density here was taken to be a quadratic function of temperature. This work as presented here is practical and relevant to many fields of study and also enhances policy making towards the protection of the aquatic ecosystems. Such scenarios are evident in lakes, especially in holomictic lakes and warm discharge from thermoelectric power generating plants. Because the sudden increase in the water temperature after discharge will leads to "thermal shock" killing aquatic life that has become acclimatised to living in a stable temperate environment. The aim of this investigation is to better fathom and as well, gain more insight into such studies. Cabbeling process was key as whenever fluid of different temperature come in contact and as well as the development of Kelvin-Helmholtz instability in the interaction surface. The general behaviours here are dependent of lock volume, density difference and Reynolds number. We noticed that the collapsing velocity of the denser fluid within the first time frame was high, higher than every fluid movement elsewhere. Relations that describes the various regimes of flow were also drawn, and as well as those for the spreading distance \(L_{d c}\) of the density current. However, there are little variations in the scaling laws as compared to the earlier studied cases where density difference was by the means of salt water. But for those where density difference is as a result of temperature, we believe that these results are a good starting point to better fathom and as well, gain more insight into such studies. Lastly, the consideration of barrier position is key, being that the lock volume is also believed to be a factor. Researchers can also gain more knowledge in terms of the dynamics of such flows.
The behaviour of warm discharge through lock-exchange was investigated numerically, with the assumption that density was taken as a quadratic function of temperature. Simulations were conducted eleven different times varying barrier position. This work as presented here is practical and can also enhance policy making towards the protection of the aquatic ecosystems. Such behaviours are evident in lakes, especially in holomictic lakes and warm discharge from thermoelectric power generating plants. The sudden increase in water temperature after discharge may leads to ”thermal shock” killing aquatic life that has become acclimatised to living in a stable temperate environment. The aim of this investigation is to better fathom and as well, gain more insight into such flows. The results show that regimes of flow is dependent on the size of the lock volume. The general behaviours here are dependent on lock volume, density difference and Reynolds number. Effects of back reflected waves on the propagation speed was not significant for small lock volume simulations. A rapid collapsing behaviour of fluid was noticed for simulations with small lock volume, and the velocity decreases with increase in lock volume in this same phase. Propagation speed is not totally independent of the lock volume. Cabbeling was also key at the point where water masses meet, and as well the development of Kelvin-Helmholtz instabilities. Relations that describes the various regimes of flow are given in Table (1 - 11). Though, there are little variations in the scaling laws as compared to the earlier studied cases where density difference was by the means of salt water. Lastly, it will be interesting if measures can be taken to eliminate the effect of this back reflected waves in other to properly fathom the behaviour in thepropagation of the frontal speed after the slumping phase.
As Grid computing continues to make inroads into different spheres of our lives and multicore computers become ubiquitous, the need to leverage the gains of multicore computers for the scheduling of Grid jobs becomes a necessity. Most Grid schedulers remain sequential in nature and are inadequate in meeting up with the growing data and processing need of the Grid. Also, the leakage of Moore’s dividend continues as most computing platforms still depend on the underlying hardware for increased performance. Leveraging the Grid for the data challenge of the future requires a shift away from the traditional sequential method. This work extends the work of [1] on a quadcore system. A random method was used to group machines and the total processing power of machines in each group was computed, a size proportional to speed method is then used to estimates the size of jobs for allocation to machine groups. The MinMin scheduling algorithm was implemented within the groups to schedule a range of jobs while varying the number of groups and threads. The experiment was executed on a single processor system and on a quadcore system. Significant improvement was achieved using the group method on the quadcore system compared to the ordinary MinMin on the quadcore. We also find significant performance improvement with increasing groups. Thirdly, we find that the MinMin algorithm also gained marginally from the quadcore system meaning that it is also scalable.
The behaviour of warm water discharged at 4\(^{\circ}\)C through lock-exchange in cold fresh water was investigated numerically, fixing lock volume at the centre of the domain. This investigation as presented here is practical and can also enhance policy making towards the protection of the aquatic ecosystems. Though, the aim of this study is to better fathom and as well, gain more insight into such ows. Our results have shown a speedy movement of the lock volume at the centre of the domain with a leading head at two front on the oor which resulted in a hat shape within the first few time frame. Fluid movement in the second phase is independent of the back reflected waves. We were able to identify two regimes of ow with a stepwise decreasing velocity in the second phase. Our results have shown that velocity with which the current travels with in the second regime is higher within the first time frame as compared to those with the effect of back reflected waves. One major factor that is responsible for decrease in the velocity here is mixing. Previous results have also shown that the front velocities in the collapsing phase are independent of lock volume. But this seem not to be the same here because fluid movement in the first phase (regime) is not totally independent of the lock volume and its position here, where density difference is as a result of temperature. However, our scaling power laws here in the second phase show some variations with previous studies where we have effect of back reflected waves. But results in the collapsing phase here are in strong agreement with those in the first phase of our previous simulations with small lock volume. Generally, the spreading behaviour here is dependent on lock volume, barrier position, density difference and Reynolds number.
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