# Questions tagged [navier-stokes]

The Navier-Stokes equations describe fluid flows in continuum mechanics.

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### How does one calculate the viscous term in the integral form of navier stokes?

I learned about the integral form of the navier stokes equation and I am trying to find an explanation for this viscous term at the end but I've searched everywhere and I can't find anything. The ...
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### Modeling fluid flow in extremely small pores (or channels) compared to the component

I want to model a non-wetting fluid flowing into tiny pores of a component using Navier-Stokes. Just for you to visualize, say I have a 2D rectangular component of dimensions $L*W$, and within that ...
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### How to calculate pressure $p$ in the Navier-Stokes equation to simulate the time evolution of a fluid?

I wanted to simulate the motion of a fluid (continuously filling the entire space) in a given space, say $3$-dimensional Euclidean space. To calculate the dynamics of fluid motion, I used the Navier-...
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### Why are the Navier-Stokes equations inconsistent in this case?

Consider the case of a one-dimensional incompressible, non-viscous fluid flowing down a vertical pipe under the influence of gravity. Since we assume the flow is constant along the cross section of ...
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### How do I calculate the Reynolds Number of fluid parcels around an aritrary object (with respect to CFD)? [closed]

Purpose: I am trying to create my own simplified rapid CFD software for custom purposes. Given an arbitrary object surrounded by a moving fluid (from an arbitrary direction in 3D), how would I best ...
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### Turbulence from a sphere spinning in an incompressible liquid

When I look online I can find plenty of simulations of Stokes flow: incompressible liquid flowing past a spherical object. What I'm interested in is the problem of a sphere (of given size) spinning (...
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### Derivation of Ladenburg correction (to calculate viscosity of fluid with Stoke's Law)

I am creating a lab report investigating the amount of time it takes for a marble ball to sink to the bottom of a cylinder container filled with sugar syrup. I recorded the amount of time it takes for ...
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### Oldroyd fluid with negative term of memory

I am looking for physical sense for the Stokes equation with memory $$\frac{d}{dt}u+u\cdot \nabla u-\mu \Delta u+\int_0^te^{-(t-s)}\Delta u(x,s)ds=f(u,t)$$ Where for now i am considering $f\equiv 0$. ...
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Incompressible Navier-Stokes in vector notation is written as $${\partial U \over \partial t}+(U\cdot\nabla)U =-\frac{1}{\rho} \nabla P + \nu \nabla^2(U),$$ where $U$ is velocity vector field $U=(u,v)... 2 votes 2 answers 164 views ### Why the derivative of the coordinate of a volume control is not zero? When deducing the Navier-Stokes equation, for conservation of momentum, in an Eulerian frame (a control volume) the derivative of fluid velocity$U_{(t)}$is calculated$$\frac{\mathrm{dU} }{\mathrm{... 4 votes 1 answer 90 views ### Hydrodynamic equation to Boltzmann's equation How to get the four-velocity of a fluid in terms of its microscopic distribution function$f(x^{i},\vec{p})$? For the sake of initial simplicity, the fluid can be thought of to be single component. ... 8 votes 3 answers 1k views ### When are my fluid approximations wrong? I did some classical approximations of the Navier Stokes equations, fluid is: non-viscous incompressible irrotational When are these approximations wrong? and particularly is there a "general ... 1 vote 1 answer 74 views ### Navier-Stokes equations - operator$P$which projects any vector field$w$onto its divergence free part$u=Pw$I have question about Navier-Stokes equation, but firstly some details: given Navier-Stokes equations:$\nabla \cdot u = 0\dfrac{\partial u}{\partial t}=-(u\cdot \nabla )u - \dfrac{1}{\rho }\...
The delta correlated Gaussian white noise $\eta(t)$ used in the study of stochastic processes is defined as the "derivative" of the Weiner process whose conditional probability density is ...