Thank you Tsing-Hsuan.

I appreciate you sharing your code. I will look into it. I will let you know if I find a more suitable solution.

Kind regards

syavash

On Tue, May 9, 2023, 16:36 Ma, Ting-Hsuan <TIM48@pitt.edu> wrote:

Hi,

I would recommend using the script method in Gmsh to add in the physical groups for 1d elements. A lot of time they are in incremental numbers, so it is easy to iterate through them. Below I'll provide the python code I wrote for my own use. I will emphasize here that you should double check the curves are set up in incremental numbers before applying the codes below.

##### Below this section is setting parameters for NekMesh #####

## Note that this could be done in Gmsh, but it's faster to automate it

## Note that Curve loop will need to be defined after all physical groups like

#  inlet, outlet, top, and bottom boundary. If this is not done in order,

#  mesh verticies will exhibit a no-slip boundary condition onto the interior

#  flow. The order is paramount!

loopRange = range(1,result.shape[0])

botRange = range(0,rows.shape[0]-1)

outRange = range(rows.shape[0]-1, (rows.shape[0]+inlet.shape[0]))

topRange = range((rows.shape[0]+inlet.shape[0]), (rows.shape[0]+inlet.shape[0]+top.shape[0])-1)

inRange = range((rows.shape[0]+inlet.shape[0]+top.shape[0])-1, result.shape[0])

idx = loopRange[-1]+2 # define physical groups for rest of the assignment

## Bottom Boundary

print("//+")

print('Physical Curve("Bottom", %d) = {' % (int(idx)), end= '')

for i in botRange:

    if i == botRange[-1]:

      print("%d" % (int(i)+1), end = '};\n')

      print("//+")

    else:

      print("%d," % (int(i)+1), end = '')

## Outlet

print('Physical Curve("Outlet", %d) = {' % (int(idx+1)), end= '')

for i in outRange:

    if i == outRange[-1]:

      print("%d" % (int(i)+1), end = '};\n')

      print("//+")

    else:

      print("%d," % (int(i)+1), end = '')

## Top Boundary

print('Physical Curve("Top", %d) = {' % (int(idx+2)), end= '')

for i in topRange:

    if i == topRange[-1]:

      print("%d" % (int(i)+1), end = '};\n')

      print("//+")

    else:

      print("%d," % (int(i)+1), end = '')

     

## Inlet

print('Physical Curve("Inlet", %d) = {' % (int(idx+3)), end= '')

for i in inRange:

    if i == inRange[-1]:

      print("%d" % (int(i)+1), end = '};\n')

      print("//+")

    else:

      print("%d," % (int(i)+1), end = '')

     

# Physical Groups

print("Curve Loop(1) = {", end="")

for i in loopRange:

    print("%d," % (int(i)), end="")

    if i == loopRange[-1]:

      print("%d" % (int(i)+1), end="};\n")

      print("//+")

print("Plane Surface(1) = {1};")

print("//+")

print('Physical Surface("Fluid", %d) = {1};' % (int(idx+4)) )