INS on hold with mesh converted to second order

[AdrienWehrle]

Hi everyone,

I have been working on an application to study the viscous deformation of a material with INS. Beforehand, I was working with elastic deformation and only needed a first-order mesh with HEX8 elements.

Now, with velocity and pressure at different orders, I would need the same mesh but converted to second order. I came across the second_order argument that I can pass into my mesh object (as visible in my input file) which seemed exactly like what I need. Unfortunately, after a few seconds to compute the Jacobian, no computer resources are being used anymore and the run is on hold. I don't get any error message, and eventually stop the run manually.

Running my input file with a simple generated mesh of elements e.g. HEX20 (commented in the input file) works just fine.

Any idea where that can come from? It seems like something is off with the second-order conversion...

I could convert my mesh to second order with some lower-level libmesh code but this is what MOOSE can do, so I would like to stick to it!

Thank you a lot in advance for your help!

[GiudGiud]

Hello

So your preconditioning is failing. By commenting it out, I get some progress.
it s quite slow, it looks like it s stalled, but it eventually moves on. Sadly it never converges.

Time Step 1, time = 1, dt = 1
 0 Nonlinear |R| = 9.649127e+05

    Computing Jacobian........                                                           [ 49.80 s] [  267 MB]
      0 Linear |R| = 9.649127e+05
      1 Linear |R| = 9.084799e+05
      2 Linear |R| = 8.897787e+05
      3 Linear |R| = 8.685389e+05
      4 Linear |R| = 8.602978e+05
      5 Linear |R| = 8.491643e+05
      6 Linear |R| = 8.365738e+05
      7 Linear |R| = 8.141169e+05
      8 Linear |R| = 7.998033e+05
      9 Linear |R| = 7.964132e+05
     10 Linear |R| = 7.802234e+05
     11 Linear |R| = 7.608386e+05
     12 Linear |R| = 7.397272e+05
     13 Linear |R| = 7.204700e+05
     14 Linear |R| = 6.812471e+05
     15 Linear |R| = 6.567327e+05
     16 Linear |R| = 6.484947e+05
     17 Linear |R| = 6.435986e+05
     18 Linear |R| = 6.219077e+05
     19 Linear |R| = 5.799100e+05
     20 Linear |R| = 5.315556e+05
     21 Linear |R| = 4.915147e+05
     22 Linear |R| = 4.540776e+05
     23 Linear |R| = 4.099865e+05
     24 Linear |R| = 3.669807e+05
     25 Linear |R| = 3.001556e+05
     26 Linear |R| = 2.420260e+05
     27 Linear |R| = 1.959621e+05
     28 Linear |R| = 1.567808e+05
     29 Linear |R| = 1.322356e+05
     30 Linear |R| = 1.079851e+05
     31 Linear |R| = 9.923634e+04
     32 Linear |R| = 9.540676e+04
     33 Linear |R| = 8.412448e+04
     34 Linear |R| = 7.024837e+04
     35 Linear |R| = 5.412502e+04
     36 Linear |R| = 4.771700e+04
     37 Linear |R| = 4.304156e+04
     38 Linear |R| = 4.022659e+04
     39 Linear |R| = 3.851984e+04
     40 Linear |R| = 3.614184e+04
     41 Linear |R| = 3.458510e+04
     42 Linear |R| = 3.268941e+04
     43 Linear |R| = 3.070540e+04
     44 Linear |R| = 3.042872e+04
     45 Linear |R| = 2.963951e+04
     46 Linear |R| = 2.873877e+04
     47 Linear |R| = 2.785786e+04
     48 Linear |R| = 2.639781e+04
     49 Linear |R| = 2.553932e+04
     50 Linear |R| = 2.414774e+04
     51 Linear |R| = 2.310876e+04
     52 Linear |R| = 2.222297e+04
     53 Linear |R| = 2.118268e+04
     54 Linear |R| = 2.082891e+04
     55 Linear |R| = 2.027160e+04
     56 Linear |R| = 1.953376e+04
     57 Linear |R| = 1.841990e+04
     58 Linear |R| = 1.762132e+04
     59 Linear |R| = 1.742589e+04
     60 Linear |R| = 1.662532e+04
     61 Linear |R| = 1.653317e+04
     62 Linear |R| = 1.643857e+04
     63 Linear |R| = 1.603051e+04
     64 Linear |R| = 1.578694e+04
     65 Linear |R| = 1.534703e+04
     66 Linear |R| = 1.533355e+04
     67 Linear |R| = 1.530373e+04
     68 Linear |R| = 1.473700e+04
     69 Linear |R| = 1.429712e+04
     70 Linear |R| = 1.382809e+04
     71 Linear |R| = 1.331695e+04
     72 Linear |R| = 1.282590e+04
     73 Linear |R| = 1.239285e+04
     74 Linear |R| = 1.217686e+04
     75 Linear |R| = 1.174498e+04
     76 Linear |R| = 1.135769e+04
     77 Linear |R| = 1.095996e+04
     78 Linear |R| = 1.049957e+04
     79 Linear |R| = 1.024966e+04
     80 Linear |R| = 9.959809e+03
     81 Linear |R| = 9.460647e+03
     82 Linear |R| = 8.578045e+03
     83 Linear |R| = 7.869823e+03
     84 Linear |R| = 7.367182e+03
     85 Linear |R| = 6.913204e+03
     86 Linear |R| = 6.088850e+03
     87 Linear |R| = 5.250878e+03
     88 Linear |R| = 4.369939e+03
     89 Linear |R| = 3.769751e+03
     90 Linear |R| = 3.393198e+03
     91 Linear |R| = 3.308062e+03
     92 Linear |R| = 3.167299e+03
     93 Linear |R| = 2.892434e+03
     94 Linear |R| = 2.553955e+03
     95 Linear |R| = 2.282976e+03
     96 Linear |R| = 2.133528e+03
     97 Linear |R| = 2.025081e+03
     98 Linear |R| = 1.938326e+03
     99 Linear |R| = 1.855594e+03
    100 Linear |R| = 1.728669e+03
    101 Linear |R| = 1.591072e+03
    102 Linear |R| = 1.534149e+03
    103 Linear |R| = 1.498318e+03
    104 Linear |R| = 1.465463e+03
    105 Linear |R| = 1.416459e+03
    106 Linear |R| = 1.371958e+03
    107 Linear |R| = 1.321113e+03
    108 Linear |R| = 1.249941e+03
    109 Linear |R| = 1.194985e+03
    110 Linear |R| = 1.152588e+03
    111 Linear |R| = 1.107416e+03
    112 Linear |R| = 1.062209e+03
    113 Linear |R| = 1.005064e+03
    114 Linear |R| = 9.581028e+02
    115 Linear |R| = 9.232967e+02
    116 Linear |R| = 8.964889e+02
    117 Linear |R| = 8.768560e+02
    118 Linear |R| = 8.654443e+02
    119 Linear |R| = 8.471908e+02
    120 Linear |R| = 8.035362e+02
    121 Linear |R| = 7.835320e+02
    122 Linear |R| = 7.702510e+02
    123 Linear |R| = 7.613471e+02
    124 Linear |R| = 7.561386e+02
    125 Linear |R| = 7.377805e+02
    126 Linear |R| = 7.195058e+02
    127 Linear |R| = 7.052307e+02
    128 Linear |R| = 6.984043e+02
    129 Linear |R| = 6.905484e+02
    130 Linear |R| = 6.753441e+02
    131 Linear |R| = 6.418160e+02
    132 Linear |R| = 6.056253e+02
    133 Linear |R| = 5.769659e+02
    134 Linear |R| = 5.542915e+02
    135 Linear |R| = 5.407478e+02
    136 Linear |R| = 5.270740e+02
    137 Linear |R| = 5.105799e+02
    138 Linear |R| = 4.942780e+02
    139 Linear |R| = 4.666186e+02
    140 Linear |R| = 4.407491e+02
    141 Linear |R| = 4.237599e+02
    142 Linear |R| = 3.988148e+02
    143 Linear |R| = 3.805127e+02
    144 Linear |R| = 3.609736e+02
    145 Linear |R| = 3.362626e+02
    146 Linear |R| = 3.110565e+02
    147 Linear |R| = 2.932049e+02
    148 Linear |R| = 2.842103e+02
    149 Linear |R| = 2.713694e+02
    150 Linear |R| = 2.458900e+02
    151 Linear |R| = 2.288432e+02
    152 Linear |R| = 2.201769e+02
    153 Linear |R| = 2.128094e+02
    154 Linear |R| = 2.054833e+02
    155 Linear |R| = 1.957295e+02
    156 Linear |R| = 1.866682e+02
    157 Linear |R| = 1.804425e+02
    158 Linear |R| = 1.765332e+02
    159 Linear |R| = 1.729278e+02
    160 Linear |R| = 1.654225e+02
    161 Linear |R| = 1.593431e+02
    162 Linear |R| = 1.519460e+02
    163 Linear |R| = 1.454851e+02
    164 Linear |R| = 1.419426e+02
    165 Linear |R| = 1.387328e+02
    166 Linear |R| = 1.346149e+02
    167 Linear |R| = 1.279908e+02
    168 Linear |R| = 1.192901e+02
    169 Linear |R| = 1.145017e+02
    170 Linear |R| = 1.113390e+02
    171 Linear |R| = 1.086403e+02
    172 Linear |R| = 1.064604e+02
    173 Linear |R| = 1.031118e+02
    174 Linear |R| = 1.003056e+02
    175 Linear |R| = 9.838820e+01
    176 Linear |R| = 9.589265e+01
    177 Linear |R| = 9.433889e+01
    178 Linear |R| = 9.300322e+01
    179 Linear |R| = 9.124034e+01
    180 Linear |R| = 8.686447e+01
    181 Linear |R| = 8.444467e+01
    182 Linear |R| = 8.368949e+01
    183 Linear |R| = 8.216528e+01
    184 Linear |R| = 7.984416e+01
    185 Linear |R| = 7.751164e+01
    186 Linear |R| = 7.603297e+01
    187 Linear |R| = 7.408958e+01
    188 Linear |R| = 7.301478e+01
    189 Linear |R| = 7.102873e+01
    190 Linear |R| = 7.001659e+01
    191 Linear |R| = 6.865305e+01
    192 Linear |R| = 6.593314e+01
    193 Linear |R| = 6.213374e+01
    194 Linear |R| = 5.943365e+01
    195 Linear |R| = 5.785247e+01
    196 Linear |R| = 5.600554e+01
    197 Linear |R| = 5.453322e+01
    198 Linear |R| = 5.308795e+01
    199 Linear |R| = 5.117584e+01
    200 Linear |R| = 4.814336e+01
    201 Linear |R| = 4.591707e+01
    202 Linear |R| = 4.467883e+01
    203 Linear |R| = 4.209664e+01
    204 Linear |R| = 4.029718e+01
    205 Linear |R| = 3.901124e+01
    206 Linear |R| = 3.782749e+01
    207 Linear |R| = 3.560136e+01
    208 Linear |R| = 3.309919e+01
    209 Linear |R| = 3.116082e+01
    210 Linear |R| = 3.019461e+01
    211 Linear |R| = 2.978197e+01
    212 Linear |R| = 2.906562e+01
    213 Linear |R| = 2.679234e+01
    214 Linear |R| = 2.486787e+01
    215 Linear |R| = 2.383209e+01
    216 Linear |R| = 2.323799e+01
    217 Linear |R| = 2.279399e+01
    218 Linear |R| = 2.227532e+01
    219 Linear |R| = 2.117646e+01
    220 Linear |R| = 2.004059e+01
    221 Linear |R| = 1.910800e+01
    222 Linear |R| = 1.861775e+01
    223 Linear |R| = 1.816517e+01
    224 Linear |R| = 1.764476e+01
    225 Linear |R| = 1.712869e+01
    226 Linear |R| = 1.627988e+01
    227 Linear |R| = 1.540058e+01
    228 Linear |R| = 1.477298e+01
    229 Linear |R| = 1.434217e+01
    230 Linear |R| = 1.392472e+01
    231 Linear |R| = 1.353750e+01
    232 Linear |R| = 1.295071e+01
    233 Linear |R| = 1.259915e+01
    234 Linear |R| = 1.230281e+01
    235 Linear |R| = 1.211274e+01
    236 Linear |R| = 1.195102e+01
    237 Linear |R| = 1.169310e+01
    238 Linear |R| = 1.131498e+01
    239 Linear |R| = 1.071288e+01
    240 Linear |R| = 9.734177e+00
    241 Linear |R| = 9.389857e+00
    242 Linear |R| = 9.211516e+00
    243 Linear |R| = 8.951693e+00
    244 Linear |R| = 8.673472e+00
    245 Linear |R| = 8.156681e+00
    246 Linear |R| = 7.902941e+00
    247 Linear |R| = 7.767071e+00
    248 Linear |R| = 7.617172e+00
    249 Linear |R| = 7.525572e+00
    250 Linear |R| = 7.418225e+00
    251 Linear |R| = 7.262558e+00
    252 Linear |R| = 7.002737e+00
    253 Linear |R| = 6.670085e+00
    254 Linear |R| = 6.477127e+00
    255 Linear |R| = 6.243982e+00
    256 Linear |R| = 5.960057e+00
    257 Linear |R| = 5.772364e+00
    258 Linear |R| = 5.524780e+00
    259 Linear |R| = 5.319289e+00
    260 Linear |R| = 5.185796e+00
    261 Linear |R| = 5.033500e+00
    262 Linear |R| = 4.848054e+00
    263 Linear |R| = 4.582003e+00
    264 Linear |R| = 4.309932e+00
    265 Linear |R| = 4.157140e+00
    266 Linear |R| = 3.968234e+00
    267 Linear |R| = 3.849262e+00
    268 Linear |R| = 3.744651e+00
    269 Linear |R| = 3.631541e+00
    270 Linear |R| = 3.485162e+00
    271 Linear |R| = 3.357093e+00
    272 Linear |R| = 3.254352e+00
    273 Linear |R| = 3.159117e+00
    274 Linear |R| = 3.065650e+00
    275 Linear |R| = 2.964147e+00
    276 Linear |R| = 2.845482e+00
    277 Linear |R| = 2.731465e+00
    278 Linear |R| = 2.648347e+00
    279 Linear |R| = 2.556385e+00
    280 Linear |R| = 2.474181e+00
    281 Linear |R| = 2.386233e+00
    282 Linear |R| = 2.291378e+00
    283 Linear |R| = 2.229858e+00
    284 Linear |R| = 2.155831e+00
    285 Linear |R| = 2.075311e+00
    286 Linear |R| = 2.013548e+00
    287 Linear |R| = 1.907614e+00
    288 Linear |R| = 1.799636e+00
    289 Linear |R| = 1.749351e+00
    290 Linear |R| = 1.695522e+00
    291 Linear |R| = 1.669935e+00
    292 Linear |R| = 1.626489e+00
    293 Linear |R| = 1.577064e+00
    294 Linear |R| = 1.552528e+00
    295 Linear |R| = 1.514183e+00
    296 Linear |R| = 1.484038e+00
    297 Linear |R| = 1.448852e+00
    298 Linear |R| = 1.387841e+00
    299 Linear |R| = 1.332219e+00
    300 Linear |R| = 1.258347e+00
    301 Linear |R| = 1.209693e+00
    302 Linear |R| = 1.162810e+00
    303 Linear |R| = 1.127644e+00
    304 Linear |R| = 1.109404e+00
    305 Linear |R| = 1.065408e+00
    306 Linear |R| = 1.032888e+00
    307 Linear |R| = 1.013135e+00
    308 Linear |R| = 9.956087e-01
    309 Linear |R| = 9.738747e-01
    310 Linear |R| = 9.649077e-01
 1 Nonlinear |R| = 9.457580e+05
etc

With the equivalent MOOSE-made mesh in terms of elements (x50 more elements than the one you have checked in though), it s faster and converges. But then when you make it the same dimension as your simulation mesh (1k m dimension roughly), you get similar bad convergence.

So this is not really a MOOSE mesh vs external mesh problem or a second order mesh problem.
It s more a convergence issue with some PCs and a very slow preconditioning once the Jacobian has been computed with others.

I would try to see if a smaller dimension system helps (using a TransformGenerator to scale the mesh for example). Then we ll have to figure out a working preconditioner, possibly using a field split.

Guillaume

[GiudGiud]

so we have 0 BCs on all sides?
But the glacier is naturally slipping by gravity to one side?

Maybe both sides on the "slipping direction" should not be velocity dirichlet BCs which preclude movement, but pressure BCs?
Pressure BCs could impose the hydrostatic pressure for example?

[AdrienWehrle]

so we have 0 BCs on all sides?

At the moment yes, to try and constrain the system...

But the glacier is naturally slipping by gravity to one side?

All sides the same at the moment since I don't have a bed slope...

Pressure BCs could impose the hydrostatic pressure for example?

I'm trying to model a part of the glacier that's called the ice stream. Both upstream and downstream from this channel there would be ice coming in and out. It's probably about finding the right influx and outflux values to get the system stable... I'm struggling to find solutions to this problem. As soon as there is a bit of movement involved it blows up...

[GiudGiud]

Would the influx and outflux be set or are you trying to determine them from this simulation?

All sides the same at the moment since I don't have a bed slope...
ok so that case works now?

Could you please share your current input? We should look at what we can achieve there

[lindsayad]

we can help you figure out what to do for proper slip conditions for the channel "walls" (left, right, bottom, top), but you will need to figure out a boundary condition for velocity for at least one end of the channel. I think that the 0 Dirichlet BCs you have on your "upstream" boundary are a great first start. Then a natural boundary condition on the "downstream" boundary might work.

For doing slip BCs, for boundaries that are collinear with a mesh axis I would apply only a 0 DirichletBC for the collinear component. For boundaries that are not collinear with a mesh axis, I would suggest trying the INSFEMomentumFreeSlipBC ... but of course now that I'm looking at the code I'm seeing that 3D is not implemented yet.

Have you tried creating a 2D model? I would try that if you haven't yet done so.