A device is presented that comprises a floating body/s that create a meniscus that is either concave or convex in a liquid surface along a perimeter of the floating body/s, and a blade/s that are connected to the floating body/s which can change the direction of a flow of fluid, where there is another meniscus on the liquid surface that is curved in an opposing direction of the first meniscus so the second meniscus is able to repel the floating object from the first meniscus. So, if the first meniscus created by the floating body/s is convex, then the other opposing meniscus on the liquid surface is concave, or if the first meniscus is concave, then the second opposing meniscus is convex. Thus, embodiments can create various movements when fluid flow interacts with the blade/s yet be repelled from areas on the liquid surface. Other embodiments are described and shown.

A combustion device having a double-layer structure includes a main body, which is double layered, including an inner-layer wall and an outer-layer wall disposed outside of and spaced from the inner-layer wall such that the inner-layer wall and the outer-layer wall include a hollow disposed therebetween. The inner-layer wall forms a fuel receptacle with an opening. A wick has an end defining fuel-drawing end inserted into the fuel receptacle through the opening.

A combustion device having a double-layer structure includes a main body, which is double layered, including an inner-layer wall and an outer-layer wall disposed outside of and spaced from the inner-layer wall such that the inner-layer wall and the outer-layer wall include a hollow disposed therebetween. The inner-layer wall forms a fuel receptacle with an opening. A wick has an end defining fuel-drawing end inserted into the fuel receptacle through the opening.

A device comprising a floating body/s that creates a meniscus that is either concave or convex in a liquid surface along a perimeter of the floating body/s, and a blade/s that are connected to the floating body/s which can change the direction of a flow of fluid, where there is another meniscus on the liquid surface that is curved in an opposing direction of the first meniscus so the second meniscus is able to repel the floating object from the first meniscus. If the first meniscus created by the floating body/s is convex, then the opposing meniscus on the liquid surface is concave, or if the first meniscus is concave, then the opposing meniscus is convex. Thus, embodiments can create various movements when fluid flow interacts with the blade/s, yet be repelled from areas on the liquid surface. Other embodiments are described and shown.