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  2. Fick's laws of diffusion - Wikipedia

    en.wikipedia.org/wiki/Fick's_laws_of_diffusion

    The flux is decay over the square root of time because a concentration gradient builds up near the membrane over time under ideal conditions. When there is flow and convection, the flux can be significantly different than the equation predicts and show an effective time t with a fixed value, [15] which makes the flux stable instead of decay ...

  3. Sheet flow - Wikipedia

    en.wikipedia.org/wiki/Sheet_flow

    The concentration of particles usually spreads out in a straight line, and the Rouse distribution works in the water column above the sheet-flow layer where the particles are less concentrated. However, velocity distribution formulas are still being refined to accurately describe particle velocity profiles in steady or oscillatory sheet flows. [2]

  4. Time of concentration - Wikipedia

    en.wikipedia.org/wiki/Time_of_concentration

    It is defined as the time needed for water to flow from the most remote point in a watershed to the watershed outlet. [1] It is a function of the topography, geology, and land use within the watershed. A number of methods can be used to calculate time of concentration, including the Kirpich (1940) [2] and NRCS (1997) [3] methods.

  5. Mass transfer coefficient - Wikipedia

    en.wikipedia.org/wiki/Mass_transfer_coefficient

    Mass transfer coefficients can be estimated from many different theoretical equations, correlations, and analogies that are functions of material properties, intensive properties and flow regime (laminar or turbulent flow). Selection of the most applicable model is dependent on the materials and the system, or environment, being studied.

  6. Permeation - Wikipedia

    en.wikipedia.org/wiki/Permeation

    Permeation will occur over time with the tires, so it is best to know the permeability of the material that will make up the tire with the desired gas to make the most efficient tires. Insulating material: Water vapour permeation of insulating material is important as well as for submarine cables to protect the conductor from corrosion.

  7. Mass balance - Wikipedia

    en.wikipedia.org/wiki/Mass_balance

    In physics, a mass balance, also called a material balance, is an application of conservation of mass [1] to the analysis of physical systems. By accounting for material entering and leaving a system, mass flows can be identified which might have been unknown, or difficult to measure without this technique.

  8. Material derivative - Wikipedia

    en.wikipedia.org/wiki/Material_derivative

    The material derivative is defined for any tensor field y that is macroscopic, with the sense that it depends only on position and time coordinates, y = y(x, t): +, where ∇y is the covariant derivative of the tensor, and u(x, t) is the flow velocity.

  9. Continuous stirred-tank reactor - Wikipedia

    en.wikipedia.org/wiki/Continuous_stirred-tank...

    The continuous stirred-tank reactor (CSTR), also known as vat-or backmix reactor, mixed flow reactor (MFR), or a continuous-flow stirred-tank reactor (CFSTR), is a common model for a chemical reactor in chemical engineering and environmental engineering. A CSTR often refers to a model used to estimate the key unit operation variables when using ...