fK|9 disunion Heat, Mass, and Momentum Transfer During the Melting of Glacial Ice in Seawater Authors' Closure
This is a very interesting and timely paper in that it treats a problem that will surely become increasingly important to those arid regions of the world tiiat are close enough to Antarctic;! to use fresh water derived from melting icebergs. The solution presented here has merits independent of the...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1045.9515 http://proceedings.asmedigitalcollection.asme.org/data/Journals/JHTRAO/27380/119_1.pdf |
| Summary: | This is a very interesting and timely paper in that it treats a problem that will surely become increasingly important to those arid regions of the world tiiat are close enough to Antarctic;! to use fresh water derived from melting icebergs. The solution presented here has merits independent of the particular application to the melting of icebergs, of course. In regard to this particular application, however, I would like to raise the question of whether free convection might be a very important factor. I might add that it enters the problem in a very complex and interesting way. It happens that the density temperature curve for water has a maximum near 4 deg C. Hence, if an infinite flat plate of ice melts in water at, say, 4 deg C the water near the ice is relatively buoyant, and a fairly typical free convection problem results with the cooler liquid near the ice floating upwards. If the water is at 10 deg C the problem becomes more complicated. In the inner part of the thermal boundary layer dp/dy is positive, but after the temperature reaches about 4 deg C dp/dy becomes negative. What is the flow pattern? When I dunked a colored ice cube in cold water (about 10 deg C) the flow of colored melt was vigorously downward. When you do this same experiment in salt water things are even more complicated. The fresh water that melts from an ice cube (or an iceberg) is a good deal lighter than the surrounding salt water. The density of the fresh water is about 1 g/cm 3 , while that of salt water with a salt content, or 35 ppt is about 1.03 g/cm 3 . When I repeated the colored ice cube experiment in salt water and injected a little food coloring near the ice for good measure, I found the flow to be strongly upwards, except possibly very near the ice where there might have been a slight downward motion. The buoyancy caused by the concentration gradient is stronger than that caused by the temperature gradient, especially if the water is fairly cold. The density difference between fresh water at 4 deg C and fresh water at ... |
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