smooth contour over zones
 

Dear all

I plotted 2D contour for the cell-centered result which has 2 zones.

As you can see from the attached picture, a contour is not smooth over the zones.

How can I make this continuously?

Below is a part of my ASCII data
---------------------------------
Title = "Grid"
Filetype = Full
Variables = "x", "y", "rho", "u", "v", "p", "Mach"
Zone T = "zone01"
Nodes= 373, Elements= 666
Datapacking=Block, Zonetype=FEQuadrilateral,
VarLocation=([3-7]=CELLCENTERED)
FACENEIGHBORCONNECTIONS= 1938
FACENEIGHBORMODE=GLOBALONETOONE
FEFACENEIGHBORSCOMPLETE=YES
DT=( DOUBLE DOUBLE DOUBLE DOUBLE DOUBLE DOUBLE DOUBLE )
~~~
Zone T = "zone02"
Nodes= 729, Elements= 1340
Datapacking=Block, Zonetype=FEQuadrilateral,
VarLocation=([3-7]=CELLCENTERED)
FACENEIGHBORCONNECTIONS= 3922
FACENEIGHBORMODE=GLOBALONETOONE
FEFACENEIGHBORSCOMPLETE=YES
DT=( DOUBLE DOUBLE DOUBLE DOUBLE DOUBLE DOUBLE DOUBLE )
~~~
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I checked connectivity list but there is no problem