Polished PMO intakes?

[911 SLANT]

Should intakes be polished for better flow? My PMO intake manifolds are brushed aluminum on inside. They came this way new. I would think a smooth polished finish would be better.

[RWebb]

nah

surface roughness would have to be much greater to push out the boundary layer

[stownsen914]

Yup, what he said

[911 SLANT]

So what your saying is the immediate vicinity of the boundary surface is not rough enough to effect velocity. Ok good, saved me alot of time. Thanks!

[MichaelSJackson]

Actually, he means a little roughness causes a thin layer of turbulence near the boundary and this promotes smoother flow for the rest of the flow. This has replaced the previous belief in polishing.

[juanbenae]

I would expect any significant advantage to them being polished would have been taken advantage of by PMO from jump.

now, drilling some "speed holes" might be something to be taken advantage of... I hear many of the cool kids are doing it...

[RWebb]

ok, here is a quick tour - can get very involved in say grad. school courses in climatology, physiology, biophysics, or fluid dynamics...

the flow regime near a surface varies with ht. above that surface (here, a tube but could be the surface of the earth or inside a blood vessel...)

we divide the regime into 2 or 3 regions:

1. closest to the surface - laminar flow
2. (optional) : mixed regime
3. further away - turbulent regime

to get more flow, you want higher velocity all thru the tube (but you may also want mixing, which is enhanced by turbulence)

so, do tiny lil' nubbins, small enough to alter diffusion of light (hence a satin or rough look) or to feel like a machinist would use his finger to feel surface irregularities, stick out enough to extend the laminar layer so far that it inhibits flow thru the cross section of the tube

based on my experience in my career studying flow regimes that affect animal biophysics - AND without any calculations, or paper envolopes to calculate on the back of - I say No to to the Flow reduction


I dunno if that clarifies things, but I hope it sufficiently obfuscates so that you no longer recall the OP

for more info contact Dr. Ed. E. Size at the Institute for [Not-gender] Fluidity

[911 SLANT]

Thanks Webb. Make much more sense now. Leave them alone. Got it!