# pressure drop [Urgent]

 Register Blogs Members List Search Today's Posts Mark Forums Read

 March 6, 2014, 14:19 pressure drop [Urgent] #1 Member   Join Date: Sep 2010 Posts: 51 Rep Power: 6 Hi all, I have a probleme in the comprehension of pressure drop, I have two relationship but i haven't the explication and origin : 1) deltaP= lamda*(L/D)*(V^2/2)* Rho(density) and; 2) deltaP= - lamda*(L/D)*(V^2/2) Please someone can explain

 March 7, 2014, 17:48 #2 Senior Member   lore Join Date: Mar 2010 Location: Italy Posts: 463 Rep Power: 9 You mean pressure drop in pipes? If so, then your first equation is the well known Darcy-Weisbach equation: http://en.wikipedia.org/wiki/Darcy–Weisbach_equation But in the form of head loss and not pressure drop (as you stated), so it should be written as: H=amda*(L/D)*(V^2/2)* Rho(density) and it refers to head losses in straight circular pipes. Note the following relationship also: deltaP=H*rho*g The second equation doesn't look right to me. stage81 likes this.

 March 10, 2014, 09:51 #3 Member   Join Date: Sep 2010 Posts: 51 Rep Power: 6 Thanks for your response, I choose to calculate the head loss in a pipe but in presence of a turbine! So i know that to calculate the head loss we use the relationship: deltaP= lamda*(L/D)*(V^2/2)* Rho(density) But in the resolution of an exercice in the solution I have this one : deltaP= - lamda*(L/D)*(V^2/2) So I don't undestund the difference between this two relations !!

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Alexis Sack OpenFOAM Running, Solving & CFD 2 September 22, 2014 09:18 sajeesh FLUENT 4 February 5, 2014 23:01 Daniel L FLOW-3D 2 December 10, 2010 05:23 bigfans FLUENT 6 August 7, 2009 07:48 Resnick Main CFD Forum 0 November 20, 2007 15:50

All times are GMT -4. The time now is 14:57.