In the first report, a horizontal buoyant jet was injected to a hot water storage tank under the condition of low jet flow. Visualizing the experiment was performed using tracer particles. Experiments were also carried out to find the unsteady temperature distribution in a tank when the positively or negatively buoyant jet was injected horizontally in the middle of the tank. One dimensional model for simulating temperature distribution was proposed, and adequacy of the model was confirmed by

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... paring the results with the experimental ones under various conditions. However, in the case of high jet flow rate, the effect of the momentum of the jet becomes stronger than the buoyancy effect and the existence of an opposite wall may influence the temperature distribution. In this report, visualizing experiments were performed to measure vortex forming near the opposite wall and an experimental formula was proposed to predict the size of vortexes under various conditions. A modified uniformly distributed injection model was proposed to cover high jet flow injection. The performance of the model was verified by comparing the results with the unsteady temperature distribution obtained experimentally. The model was also compared with the measurements obtained using a commercially available hot water storage tank. Both results show good agreements. Hence adequacy of the model was clarified.