Surface waves and wave resistance in magnetic fluids
We present here the experimental determination of the dispersion relation of surface waves of a ferrofluid submitted to a steady vertical magnetic field. The results are compared to a linear theory where all the magnetic characteristics of the fluid have been taken into account. The knowledge of the dispersion equation is then used to analyse the capillary-wave resistance, that is the drag force associated to the emission of waves by a moving disturbance at a free fluid surface. It undergoes a transition from zero to a finite value as the speed of the disturbance reaches a certain critical value. The effect of viscosity is explored, and a magnetic fluid is shown to allow controlling the critical speeds. Contrary to the theoretical model, however, the measured wave resistance reveals a non monotonic speed dependence after the threshold.
| Main Authors: | , , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Sociedade Brasileira de Física
2001
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| Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332001000300016 |
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