# Reynolds Number Calculation

1. Oct 17, 2009

### Ksum006

Does anyone here know how to calculate the reynolds number for a pulsating swirl flow? I've been trying to find the right expression for ages, I can't locate it.

I'm sure it will be a integral equations based upon the frequency of swirl (i.e. 1Hz, 5Hz or 10Hz etc)

Thanks

2. Oct 17, 2009

### Cyrus

The Reynolds number is simply

Re = rho*D*V/mu

I have no idea why you think it involves an integral based equation. The reynolds number is a smiliarity parameter. At a given reynolds number, the flow will exhibit pulsations and swrill. This is fundamental to what the Re No. means, and I don't think you are appreciating that fact. If your flow has rotation, then there can (possibly) be an additional nondimensional term that has to do with rotational frequencies.

$$\frac{\omega*l}{V}$$ ​

Strouhal number (unsteady oscillatory flow effects). You really need to understand the flow of your problem better to identify the key nondimensional parameters in addition to Re to describe the flow physics of your experiment.

Last edited: Oct 18, 2009