Advective flux, defined

Advection is generally defined as the displacement of a portion of matter with respect to the point of observation under the influence of force fields (Lerman, 1979). An advection flux g/(sec X cm )] of a material with density p (g/cm ) moving at velocity V (cm/sec) with respect to the point of observation is given by... 

The rate of transfer of solutes between soil and overlying water column and from one physical or chemical state to another is defined as flux. The dimensions of flux are M T where M is the mass of material transferred by flux, L is the distance or length, and T is the time. The processes associated with flux are advection, diffusion, and dispersion. Diffusive and advective flux between soil and overlying water and elemental uptake by rooted wetland vegetation are the major transport... 

The component flow rates in composition of water through any facet of the cube are subject to identical laws. If the flow was not accompanied by hydrodynamic dispersion, this flow rate of advective flux would be defined by Darcy s law, i.e., namely by the equation ... 

From these relationships and by analogy to Eqs. 19-22 in Appendix B of Palermo et al. [1], the concentration in the biotmbation layer can be estimated. hi Appendix B, however, only diffusion and bioturbation by particles were considered. Here the more compUcated case is necessary because of the additional operative processes. Rewriting Eq. 14, defining the steady-state flux as the maximum of the diffusive or advective flux in the chemical isolation layer... 

Nine boimdary conditions of the 3D SMART model are relevant for the concerned sea-atmosphere simulation. The horizontal open boundary condition 0 = 3c/3n =o with n J. 5/2 defines the gradient at the boundary to be zero for both water and air. This suppresses dispersion but permits advection through the open boundary. The no-flux boundary condition 0 = uc — Ddcdn g assures that neither dispersive nor advective flux passes through a solid boundary. At the sea and air boundary layer, dispersion is replaced with the Henry coefficient equilibrium assumption c , = Cat/h. This requires that natural gas is simulated in both, sea and atmosphere. The vertical open boundary condition for the atmosphere extrapolates the vertical gradient to the other side of the... 

The overall advective flux equation combining dry and wet deposition is defined using the vapor concentration in the air, Ca, in mg/m. This air concentration measurement is typically performed to assess the chemical mass source strength in the atmosphere. The equation is ... 

Let us consider a medium moving with velocity v (components vx, Vy, vz). A medium with non-zero velocity is said to be advective. Let us first define in the most general way the flux of volume at a point M of the familiar 3D space this is simply the quantity of volume moving across the unit surface perpendicular to v per unit time. For an arbitrary surface 6S next to M and perpendicular to v (Figure 8.1) and during time dt, the volume will be... 

It is also possible to define a fluctuating component for each quantity as the difference between the instantaneous value and the Reynolds-average value Uf = Uf - (Uf) and = np. These quantities are used for Reynolds decomposition of higher-order terms (UfWf) = turbulent flux of the NDF. Physically, this term denotes the advection of fluid elements with a given n by fluid velocity fluctuations, and thus enters the transport equation as a spatial flux. The Reynolds-average NDF can be found from Eq. (2.44) ... 

The solubility pump is defined as the exchange of carbon between the atmosphere and the ocean as mediated by physical processes such as heat flux, advection and diffusion, and ocean circulation. It assists in the transfer of atmospheric GO2 to the deep ocean. This transfer is controlled by circulation patterns of the surface ocean (wind-driven... 

Biogeochemical processes can produce large gradients in the concentration of various dissolved substances across the soil-water interface. The rate of transfer of solute between the soils and water column and from one physical-chemical state to another is defined as flux. The major processes governing flux of solutes in wetlands are sedimentation, advection, diffusion, bioturbation, water flow, and evapotranspiration. 

The temperature distribution in the fuel cell is described by the equations for the conservation of energy, which results in the heat transfer equations with heat production from the electrochemical reactions and other sources and sinks (ohmic and protonic heating, irreversible reaction heat, and reaction entropy, and heat transfer between the phases) [145]. The heat transfer equations are defined for porous and free media, and in solids. The flux may take into account heat transfer by conduction, advection, and radiation. Alternatively, and depending on the size of the cell and experimental setup, heat transfer can be described using two different temperature fields in two coupled thermal balances, where sources and sinks in the respective thermal balance represent transfer of heat between the two phases. This is done in the presence of large temperamre difference between the gas temperature (fluid-(gas)-phase temperature) and the cell operating temperature (sohd-phase temperature). 

The Vy was defined above and is always greater than the Darcian velocity, Vd- For soluble chemicals or those affixed to colloids in the porewater, the VbCw product in Equation 11.2 reflects the advective movement rate within the bed. It may be rapid compared to molecular diffusion even for moderate Q/A water fluxes. 

The dust resuspension process is one of two very significant processes that mobilize chemicals from soil surfaces to the atmospheric boundary layer. The other is termed chemical vaporization or volatilization. In the case of creating and using multimedia chemodynamic models, the flux expression must be either an advective or diffusive type relationship, containing a chemical fugacity or concentration as the state variable see Chapters 3 and 4. With the availability of Fp, it is possible to obtain the dust resuspension MTC as follows. It is defined as the ratio of the particle flux to the soil particle density or grain density Op (kg m ) ... 

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