Navier stokes Definition and 63 Threads

  1. Saladsamurai

    Navier Stokes EquationQuestion about the Diff EQ

    Hello! :smile: I am going over an example in my fluid mechanics text and I am confused about a few lines. My question is more about the math then the fluid mechanics. In fact, I doubt you need to understand the FM at all; if you understand Diff eqs, you can probably answer my question. I am...
  2. J

    The Statistics of Navier Stokes Equations

    I am curious about what insight people might have as to the statistics of Navier Stokes equation. I thought of the following way someone might try to calculate these. 1) Choose a bais (Basis A) 2) Pick a discrete number of points to constrain the solution of stokes equation. 3) Find the...
  3. J

    COMSOL doing periodic boundary conditions in navier stokes

    Please can anyone tell me how to set this up? I know how to do the required settings in the Physics/Period Conditions. However, to fully implement it, I'm also required to choose boundary conditions in the 2D incompressible navier stokes solver (e.g. wall, inlet, outflow, open boundary...
  4. O

    Navier Stokes with chemical reaction

    I wasn't sure whether to put this in Aerospace, but decided on physics in the end. 1.) How do you factor a chemical reaction into the solution for the Navier Stokes equations? More precisely, how can you include the affects of a heat absorbing (endothermic), or heat releasing (exothermic)...
  5. B

    Navier Stokes Equations - Helmholtz-Hodge decomposition and pressure

    Hi, I've been doing some work with the NS equations. I've read a few papers by fellow undergrads that imply a relationship between the helmholtz-hodge decomposition and the pressure equation. As far as I can see, they're both separate ways of resolving the problem of keeping the flow...
  6. G

    Navier Stokes Equations - General Question

    (This is from the perspective of Geophysical Fluid Dynamics) In the Navier Stokes equations I am confused as to why there is both a pressure term and a gravity term. Is this pressure resulting from differences in densities and temperature differences alone? I would think that the gravity term...
  7. H

    Navier Stokes, separation steady/non-steady

    Hello, I want, for obscur reasons which would lead us too far to explain, to split my flow into two component, one steady and another one non-steadyv = v_0 + v' I'm looking for a simple equation governing the evolution of this non steady components. The complete momentum equation gives...
  8. J

    Evolution of pressure in navier stokes

    Hello, I haven't studied PDEs much yet, but checked out what the Navier Stokes equations are. I think I understood meaning of the terms in Navier Stokes equations, and what is their purpose in defining the time evolution of velocity of the fluid, but I couldn't see any conditions for the...
  9. S

    Using Navier Stokes for rigid body with constant angular speed

    I've seen several examples of using Navier Stokes in a rotating container where gravity is purely in the Z direction. These solutions generally used cylindircal coordinate systems. I wanted to attempt this problem where the gravity vector does not point purely in the Z direction. (ie...
  10. S

    Can Navier Stokes equations explain pressure on a stationary body's surface?

    Consider a stationary body within the flow of some fluid. I want to calculate pressure on the surface of the body. From the Navier Stokes (incompressible, stationary, no volume forces) equations, you would get something like: dp/dx=-rho(u du/dx+v du/dy+w du/dz)+eta(d²u/dx²+d²u/dy²+d²u/dz²)...
  11. S

    Compressible Navier Stokes in cylinder coordinates

    Hello, I need the Navier Stokes equations for compressible flow (Newtonian fluid would be ok) in cylinder coordinates. Can anybody help? Thanks
  12. S

    How to Convert Cartesian Navier-Stokes to Cylindrical/Spherical Coordinates?

    Hi, I'm trying to understand how to convert the cartesian form of the N-S equation to cylinderical/spherical form. Rather than re-derive the equation for spherical/cylindrical systems, I am trying to directly convert the cartesian PDE. I'm ok with converting the d/dx and d2/dx2 terms. What...
  13. B

    Understanding the Vector Laplacian in the Navier Stokes Equations

    I recently came across the vector version of the Navier Stokes equations for fluid flow. \displaystyle{\frac{\partial \mathbf{u}}{\partial \mathbf{t}}} + ( \mathbf{u} \cdot \bigtriangledown) \mathbf{u} = v \bigtriangleup \mathbf{u} - grad \ p Ok, all is well until \bigtriangleup. I know...
Back
Top