Changes between Version 34 and Version 35 of u/ehansen/buildcode


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Timestamp:
10/19/12 21:12:06 (12 years ago)
Author:
ehansen
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  • u/ehansen/buildcode

    v34 v35  
    1010These are the so called Euler Equations.  They are also known as the fluid equations in conservative-law form.  These are conceptually simple and make intuitive sense.
    1111|| Name of Law || Formula ||
    12 || Conservation of Mass || [[latex($\frac{\partial}{\partial t}\rho + \frac{\partial}{\partial x} (\rho v) = 0$)]] ||
    13 || Conservation of Momentum || [[latex($\frac{\partial}{\partial t} (\rho v) + \frac{\partial}{\partial x} (\rho v^2 + p) = 0$)]] ||
    14 || Conservation of Energy || [[latex($\frac{\partial}{\partial t} E + \frac{\partial}{\partial x} (v(E+p)) = 0$)]] ||
    15 Where [[latex($\rho$)]] is mass density, v is velocity (only in x-direction for 1D), p is pressure, and E is total energy per unit volume. E is further defined as [[latex($E = \rho (\frac{1}{2} v^2 + e)$)]] where e is the specific internal energy.  The specific internal energy depends on the equation of state.  For an ideal gas [[latex($e = \frac{p}{\rho(\gamma - 1)}$)]] where [[latex($\gamma$)]] is the ratio of specific heats.  Basically, these laws state that in a given volume, the change in a conserved quantity must be equal to the flux through the boundaries of that volume.  In other words, the conserved quantity is in front of the time derivative and its flux is in front of the spatial derivative.
     12|| Conservation of Mass || [[latex(\frac{\partial}{\partial t}\rho + \frac{\partial}{\partial x} (\rho v) = 0)]] ||
     13|| Conservation of Momentum || [[latex(\frac{\partial}{\partial t} (\rho v) + \frac{\partial}{\partial x} (\rho v^2 + p) = 0)]] ||
     14|| Conservation of Energy || [[latex(\frac{\partial}{\partial t} E + \frac{\partial}{\partial x} (v(E+p)) = 0)]] ||
     15Where [[latex(\rho)]] is mass density, v is velocity (only in x-direction for 1D), p is pressure, and E is total energy per unit volume. E is further defined as [[latex(E = \rho (\frac{1}{2} v^2 + e))]] where e is the specific internal energy.  The specific internal energy depends on the equation of state.  For an ideal gas [[latex(e = \frac{p}{\rho(\gamma - 1)})]] where [[latex(\gamma)]] is the ratio of specific heats.  Basically, these laws state that in a given volume, the change in a conserved quantity must be equal to the flux through the boundaries of that volume.  In other words, the conserved quantity is in front of the time derivative and its flux is in front of the spatial derivative.
    1616
    1717The Euler equations can also be written in integral form for a general control volume  [[latex($[x_1,x_2] \ \mathrm{x} \ [t_1,t_2]$)]] .  To simplify the notation, let U be a vector containing the conserved quantities and F be the vector of the corresponding fluxes. Now the Euler equations are: