Search results
Results From The WOW.Com Content Network
An acoustic metamaterial, sonic crystal, or phononic crystal is a material designed to manipulate sound waves or phonons in gases, liquids, and solids (crystal lattices).By carefully controlling properties such as the bulk modulus β, density ρ, and chirality, these materials can be tailored to interact with sound in specific ways, such as transmitting, trapping, or amplifying waves at ...
This is the only type of static compression that liquids and gases can bear. [3] It affects the volume of the material, as quantified by the bulk modulus and the volumetric strain. The inverse process of compression is called decompression, dilation, or expansion, in which the object enlarges or increases in volume.
Normally, light traveling from, say, air into water bends upon passing through the normal (a plane perpendicular to the surface) and entering the water. In contrast, light reaching a negative index material through air would not cross the normal. Rather, it would bend the opposite way.
The boundary layer is a very thin sheet of air lying over the surface of the wing (and all other surfaces of the aircraft). Because air has viscosity, this layer of air tends to adhere to the wing. As the wing moves forward through the air, the boundary layer at first flows smoothly over the streamlined shape of the airfoil. Here, the flow is ...
Depending on the size of the velocity difference and the size of the density contrast between the layers, Kelvin-Helmholtz waves can look different. For instance, between two layers of air or two layers of water, the density difference is much smaller and the layers are miscible; see black-and-white model video.
The SI unit for permeability is the square metre (m 2).A practical unit for permeability is the darcy (d), or more commonly the millidarcy (md) (1 d ≈ 10 −12 m 2). The name honors the French Engineer Henry Darcy who first described the flow of water through sand filters for potable water supply.
This requires the Knudsen number to be small, as is also a pre-requisite for the continuum hypothesis to be a valid one. [2] [4] [5] Further note, that unlike the mathematical concept of a fluid parcel which can be uniquely identified—as well as exclusively distinguished from its direct neighbouring parcels—in a real fluid such a parcel ...
Note this is valid only for one dimensional fluid flow in rectangular coordinates. The τ {\displaystyle \tau } is the shear stress at any layer of the fluid where d u / d y {\displaystyle du/dy} (i.e. the gradient of velocity in a direction perpendicular to the flow and the area of the flat plate), is the local gradient and μ {\displaystyle ...