From hot region to cold region ?

[jangheej]

it's widely known that a body (whether it's a particle or fluid) moves from a hot region to a cold region.
But while doing an experiment, I observed otherwise.
The experiment is plunging a hot wire into a beaker filled with water with powder floating on the surface. When I put the hot wire, the powder did not immediately move away from the wire, but first moved toward the wire and then bounced off.
Why is it that the particles are first attracted to the wire?

Could it be related to a change in surface tension?

If so, specifically how does the surface tension change?

And how can I quantitatively measure the effect of the plunging in the experiment so that I can only consider the effect of heat energy transfer?

 

[Valerie Park]

Surface tension plays an important role in this phenomenon. As the hot wire is inserted into the beaker, it causes the surface of the liquid to heat up, which leads to a decrease in surface tension. This decrease in surface tension causes the powder particles to move toward the hot wire as they are then able to move more freely through the lower surface tension. The particles then bounce off the wire when the surface tension begins to build back up as the wire cools. In order to quantitatively measure the effect of the plunging in the experiment, you should measure the temperature of the water before and after the wire is plunged in, and also measure the temperature of the wire itself. Additionally, you can measure the distance traveled by the particles and the time taken for them to reach the wire after the plunge. By collecting this data, you can calculate the rate of heat transfer from the wire to the water and the effect this has on the surface tension.