How to Plot Graphs of Parameters (Not Convergence) in ANSYS CFX?

Shomaz ul Haq · December 22, 2015, 02:41

Dear all,

Hi. Hope everyone is well. I wanted to ask how can I plot graphs of four parameters: pressure drop (ΔP), friction factor (f), heat transfer coefficient and Nusselt number (Nu) versus Reynolds number for a counter flow double pipe heat exchanger? Should I use formulas or is there any option where automatically these graphs can be plotted? I have successfully made the model and now want to plot graphs. Would be grateful for help by expert people. God bless you all. Thanks.

ghorrocks · December 22, 2015, 05:34

It is best if you develop the formulas for these parameters yourself. Then you know exactly what parameters went into them.

Shomaz ul Haq · December 22, 2015, 05:53

Thanks for the reply Ghorrocks. I wanted to ask how should I use the formulas and what is the procedure? Is there any way to select parameters on x and y axis and then plot? I have never done this, so don't know how. For example h=q"/(T_wall-T_bulk) and Re=ρVD/μ. From where would I get the parameters used in the formulas and how to plot these graphs? Would be grateful for help. Thanks.

ghorrocks · December 22, 2015, 06:29

You can use CFD-Post to graph these things but I do all my plotting in other packages like tecplot and python.

For Re = rho*V*D/mu - you need to define expressions which evaluate these input variables. Then a simple expression gives you Re. Have a look in the tutorials for examples of CEL expressions.

Shomaz ul Haq · December 22, 2015, 09:50

Thanks Ghorrocks. Where would I get ρ, V, D, and μ from? and after I make expressions how to plot them. Would be grateful for your help. God bless you. Thanks.

ghorrocks · December 22, 2015, 18:01

You get those values from whatever is an appropriate definition of them to get Re in your case. If the flow is incompressible then density is obvious, if compressible you could use either a domain average or the free stream density. Velocity is probably the free stream velocity, or the average velocity over the pipe cross section. D is an appropriate length scale - either a length, width or diameter.

Shomaz ul Haq · December 24, 2015, 09:46

Thanks Glenn. I have made the expressions. Now how should I plot heat transfer coefficient versus Re? Do I need to plot in CFX-Solver or CFX-Post? Would be grateful for help. God bless you. Thanks.

sunilpatil · December 25, 2015, 04:58

you can plot it in CFD-post not in CFX-pre

Shomaz ul Haq · December 25, 2015, 10:02

Thanks all. How can I plot graphs of variables in CFX-Post?

December 22, 2015, 02:41	How to Plot Graphs of Parameters (Not Convergence) in ANSYS CFX?	#1
Shomaz ul Haq Senior Member Shomaz ul Haq Join Date: Aug 2015 Location: Islamabad, Pakistan Posts: 205 Rep Power: 12	Dear all, Hi. Hope everyone is well. I wanted to ask how can I plot graphs of four parameters: pressure drop (ΔP), friction factor (f), heat transfer coefficient and Nusselt number (Nu) versus Reynolds number for a counter flow double pipe heat exchanger? Should I use formulas or is there any option where automatically these graphs can be plotted? I have successfully made the model and now want to plot graphs. Would be grateful for help by expert people. God bless you all. Thanks.

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December 22, 2015, 05:34		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	It is best if you develop the formulas for these parameters yourself. Then you know exactly what parameters went into them.

December 22, 2015, 05:53		#3
Shomaz ul Haq Senior Member Shomaz ul Haq Join Date: Aug 2015 Location: Islamabad, Pakistan Posts: 205 Rep Power: 12	Thanks for the reply Ghorrocks. I wanted to ask how should I use the formulas and what is the procedure? Is there any way to select parameters on x and y axis and then plot? I have never done this, so don't know how. For example h=q"/(T_wall-T_bulk) and Re=ρVD/μ. From where would I get the parameters used in the formulas and how to plot these graphs? Would be grateful for help. Thanks.

December 22, 2015, 06:29		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	You can use CFD-Post to graph these things but I do all my plotting in other packages like tecplot and python. For Re = rhoVD/mu - you need to define expressions which evaluate these input variables. Then a simple expression gives you Re. Have a look in the tutorials for examples of CEL expressions.

December 22, 2015, 09:50		#5
Shomaz ul Haq Senior Member Shomaz ul Haq Join Date: Aug 2015 Location: Islamabad, Pakistan Posts: 205 Rep Power: 12	Thanks Ghorrocks. Where would I get ρ, V, D, and μ from? and after I make expressions how to plot them. Would be grateful for your help. God bless you. Thanks.

December 22, 2015, 18:01		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	You get those values from whatever is an appropriate definition of them to get Re in your case. If the flow is incompressible then density is obvious, if compressible you could use either a domain average or the free stream density. Velocity is probably the free stream velocity, or the average velocity over the pipe cross section. D is an appropriate length scale - either a length, width or diameter.

December 24, 2015, 09:46		#7
Shomaz ul Haq Senior Member Shomaz ul Haq Join Date: Aug 2015 Location: Islamabad, Pakistan Posts: 205 Rep Power: 12	Thanks Glenn. I have made the expressions. Now how should I plot heat transfer coefficient versus Re? Do I need to plot in CFX-Solver or CFX-Post? Would be grateful for help. God bless you. Thanks.

December 25, 2015, 04:58		#8
sunilpatil Senior Member sunil Join Date: Jul 2012 Location: Bangalore Posts: 179 Rep Power: 14	you can plot it in CFD-post not in CFX-pre

December 25, 2015, 10:02		#9
Shomaz ul Haq Senior Member Shomaz ul Haq Join Date: Aug 2015 Location: Islamabad, Pakistan Posts: 205 Rep Power: 12	Thanks all. How can I plot graphs of variables in CFX-Post?