[harsha_kulkarni]

What is the difference between QUICK and upwind scheme

[LuckyTran]

Hi friend, Google is your friend.

QUICK scheme

[FMDenaro]

Originally Posted by harsha_kulkarni

What is the difference between QUICK and upwind scheme

The term "upwind" is a general nomenclature to address the asymmetric computational stencil, oriented upwinded according to the direction of the flow.

In such framework, QUICK is a scheme based on the upwind criterion.

[aerosayan]

Originally Posted by harsha_kulkarni

What is the difference between QUICK and upwind scheme

Disclaimer : Not an expert


Based on stability analysis, experts have observed that the CFD schemes tend to be unstable and inaccurate if they don't represent the physics correctly.


central difference limitations :



In the case of flow physics, it was observed that something like a central difference scheme wasn't giving the accurate results, because the downstream cells don't know what's happening upstream, due to the finite amount of time required to transfer the fluid information from the upstream position to the downstream position.


This is very easily observed in cases of supersonic flows. Across shockwaves, there is such a high discontinuity between the properties, that central difference schemes don't work.


Imagine there's a shockwave, across which, the temperature rises by 300 Kelvin from room temperature.


Since central difference schemes are basically fancy weighted averages, there will be a huge error if we use it to calculate the temperature in the cells near the shockwave.


Thus, it makes sense, to use the values from the upstream side, on the upstream side, and values from the downstream side, on the downstream side.


Similarly, since the flow information travels at the speed of sound.


So, in a supersonic flow, the downstream cells don't know of the flow information in the upstream cells. So, using a central difference makes no sense, we only take the flow information from the upstream cells.


That's upwinding scheme.


QUICK scheme:



QUICK is a kind of upwinding scheme that uses a quadratic interpolation to calculate the flow properties for a face. Due to the interpolation being quadratic in nature, it is more accurate than a linear interpolation used commonly in basic upwind schemes, but it suffers from oscillations, as it is quadratic in nature.