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Help! 6 equation non-linear system

• To: mathgroup at smc.vnet.net
• Subject: [mg99681] Help! 6 equation non-linear system
• From: Marc <dunh0037 at umn.edu>
• Date: Mon, 11 May 2009 06:23:16 -0400 (EDT)

I'm very new to Mathematica, and I'm trying to solve a fairly complex
system involving 3 non-linear implicit equations (Colebrook
equations). I've tried just doing a Solve and NSolve function, but my
Core 2 Duo @ 2.2GHz with 3 GB ram running on XP runs out of memory and
can't produce anything.

Here are my equations:

190200=999*V3^2/2-999*V1^2/2+33266.7*f3*V3^2+166533*f1*V1^2+14185.2*V3^2

180400=999*V2^2/2-999*V1^2/2+199800*f2*V2^2+166533*f1*V1^2+25874.1*V2^2

V1=V2+V3

1/sqrt(f1)=-2*log(2.7*10^-5+1.88*10^-4/(V1*sqrt(f1)))

1/sqrt(f2)=-2*log(2.7*10^-5+1.88*10^-4/(V2*sqrt(f2)))

1/sqrt(f3)=-2*log(2.7*10^-5+1.88*10^-4/(V3*sqrt(f3)))


Variables:

V1: should be in the range 0 < V1 < 20
V2: should be in the range 0 < V2 < 10
V3: should be in the range 0 < V3 < 10
f1: should be in the range 0 < f1 < 0.1
f2: should be in the range 0 < f2 < 0.1
f3: should be in the range 0 < f3 < 0.1


Any help would be greatly appreciated, I'm stuck!!

• Follow-Ups:
  • Re: Help! 6 equation non-linear system
    • From: Daniel Lichtblau <danl@wolfram.com>