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# How to plot axial velocity profiles

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Bernard Hippolyte on 31 Jul 2019
Commented: infinity on 2 Aug 2019
Hello,
I am studying flow conditions over a flat plate. In my analysis I'd like to make a graph representing the velocity profile at different locations along the x-axis.
I have 3 velocity vectors for 3 different locations along the x-axis, whose values change according to the height with respect to the flow surface. I have created a first plot with that code :
z = [0,9.99999953400000e-05,0.000219999991200000,0.000363999986200000,0.000536799977600000,0.000744159964100000,0.000992991944000000,0.00129159031500000,0.00164990835500000,0.00207988999700000,0.00259586796200000,0.00321504151600000,0.00395804977800000,0.00484965968200000,0.00591959154100000,0.00720350974200000,0.00874421157500000,0.0105930537600000,0.0120000000000000];
v1 = [0,0.00325397021600000,0.00701125750100000,0.0113216226500000,0.0162260455500000,0.0217406444100000,0.0278199545200000,0.0343086455900000,0.0409495839500000,0.0474558756800000,0.0535523554300000,0.0589996739700000,0.0636245292600000,0.0673341282000000,0.0701542241100000,0.0722371526700000,0.0737607573100000,0.0748035608600000,0.0750795450500000];
v2 = [0,0.00366377801700000,0.00791285352500000,0.0128013963500000,0.0183614737800000,0.0245786185200000,0.0313532627000000,0.0384678052200000,0.0456212766800000,0.0525096049400000,0.0588643367300000,0.0644851997700000,0.0692671336100000,0.0731802814600000,0.0762524020600000,0.0785669430900000,0.0802213325000000,0.0812515896100000,0.0814175550000000] ;
v3 =[0,0.00520340445400000,0.0111829468300000,0.0179754812400000,0.0255750928700000,0.0338966479500000,0.0427261762400000,0.0517216408400000,0.0604887040700000,0.0686496402800000,0.0758974471700000,0.0820465381000000,0.0870401606400000,0.0909297100700000,0.0938583875400000,0.0960021018900000,0.0974763949700000,0.0983292911300000,0.0984241062400000] ;
plot(v1,z,v2,z,v3,z)
legend('x = 0 mm','x = 50 mm','x = 100mm')
xlabel('velocity [m/s]')
ylabel('height [m]')
But contrary to what my matlab code does, I would like to create a new axis (x-axis) representing the location of each velocity profile as shown in the following figure :
Despite my research on the web I didn't found any solution... I will be grateful to you for your help.
Thanks so much,
Hippolyte

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### Answers (1)

infinity on 1 Aug 2019
Hello,
You can refer this code
z = [0,9.99999953400000e-05,0.000219999991200000,0.000363999986200000,0.000536799977600000,0.000744159964100000,0.000992991944000000,0.00129159031500000,0.00164990835500000,0.00207988999700000,0.00259586796200000,0.00321504151600000,0.00395804977800000,0.00484965968200000,0.00591959154100000,0.00720350974200000,0.00874421157500000,0.0105930537600000,0.0120000000000000];
v1 = [0,0.00325397021600000,0.00701125750100000,0.0113216226500000,0.0162260455500000,0.0217406444100000,0.0278199545200000,0.0343086455900000,0.0409495839500000,0.0474558756800000,0.0535523554300000,0.0589996739700000,0.0636245292600000,0.0673341282000000,0.0701542241100000,0.0722371526700000,0.0737607573100000,0.0748035608600000,0.0750795450500000];
v2 = [0,0.00366377801700000,0.00791285352500000,0.0128013963500000,0.0183614737800000,0.0245786185200000,0.0313532627000000,0.0384678052200000,0.0456212766800000,0.0525096049400000,0.0588643367300000,0.0644851997700000,0.0692671336100000,0.0731802814600000,0.0762524020600000,0.0785669430900000,0.0802213325000000,0.0812515896100000,0.0814175550000000] ;
v3 =[0,0.00520340445400000,0.0111829468300000,0.0179754812400000,0.0255750928700000,0.0338966479500000,0.0427261762400000,0.0517216408400000,0.0604887040700000,0.0686496402800000,0.0758974471700000,0.0820465381000000,0.0870401606400000,0.0909297100700000,0.0938583875400000,0.0960021018900000,0.0974763949700000,0.0983292911300000,0.0984241062400000] ;
plot(v1,z,v2+0.2,z,v3+0.4,z)
legend('x = 0 mm','x = 50 mm','x = 100mm')
xticks([0 0.1 0.2 0.3 0.4 0.5])
xticklabels({'0','0.1','0','0.1','0','0.1'})
xlabel('velocity [m/s]')
ylabel('height [m]')

#### 2 Comments

Bernard Hippolyte on 1 Aug 2019
Thank you for your answer but to be clearer :
I'd like to have a top x-axis with the changing location and a bottom x-axis representing the velocity as a function of y-axis at each location.
It means that for each new location, the maximal interval of velocity has to start again on its axis. In the code I gave you, this interval is meet for v3 : [0m/s to 0.098m/s or 0.1m/s].
My comments are well exposed in the figure I have attached where we can see the velocity varying between 0 and 1 for each location.
Best regards
infinity on 2 Aug 2019
Hello,
I am still not get your point. But, maybe someone else can help you.
Good luck

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