Hi, I am not sure on that, but I do recall that the Lagrange basis might be only implemented for quadrilateral in 2D and cuboid (?) in 3D elements. Best regards, Stanisław Gepner, Ph.D. *Faculty of Power and Aeronautical Engineering* Nowowiejska 21/25 Str. 00-665 Warsaw, Poland phone +48 (22) 234 51 70 <https://www.pw.edu.pl/engpw> On 28.03.2023 12:15, Ehsan Asgari wrote:

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Dear All,

I am trying to compare the performance of different expansion types. However, when I set TYPE="GLL_LAGRANGE_SEM", I get the following error:

=======================================================================                 EquationType: UnsteadyNavierStokes                 Session Name: MeshWith3PrismsLayers                 Spatial Dim.: 3           Max SEM Exp. Order: 5               Num. Processes: 128               Expansion Dim.: 3              Projection Type: Continuous Galerkin          Advect. advancement: explicit         Diffuse. advancement: implicit                    Time Step: 0.0005                 No. of Steps: 1000000          Checkpoints (steps): 1000             Integration Type: IMEX             Splitting Scheme: Velocity correction (strong press. form) ======================================================================= Initial Conditions:   - Field u: 1.0   - Field v: 0.0   - Field w: 0.0   - Field p: 0.0 renaming "MeshWith3PrismsLayers_0.chk" -> "MeshWith3PrismsLayers_0.bak0.chk" Writing: "MeshWith3PrismsLayers_0.chk"  (0.186233s, HDF5) [gra723:25064:0:25064] Caught signal 11 (Segmentation fault: address not mapped to object at address 0x3025)

Here is my setup:

<?xml version="1.0" encoding="utf-8" ?> <NEKTAR>   <EXPANSIONS>     <E COMPOSITE="C[30011]" NUMMODES="5" TYPE="GLL_LAGRANGE_SEM" FIELDS="u,v,w,p" />   </EXPANSIONS>   <CONDITIONS>         <FUNCTION NAME="InitialConditions">                 <E VAR="u" VALUE="1.0" />                 <E VAR="v,w,p" VALUE="0.0" />         </FUNCTION>     <SOLVERINFO>       <I PROPERTY="SolverType"  VALUE="VelocityCorrectionScheme"/>       <I PROPERTY="EqType"  VALUE="UnsteadyNavierStokes"    />       <I PROPERTY="Projection"  VALUE="Continuous"              />       <I PROPERTY="EvolutionOperator" VALUE="Nonlinear"               />       <I PROPERTY="TimeIntegrationMethod" VALUE="IMEXOrder2"              />       <I PROPERTY="GlobalSysSoln" VALUE="IterativeStaticCond" />       <I PROPERTY="Driver"  VALUE="Standard"                />   </SOLVERINFO>     <GLOBALSYSSOLNINFO>           <V VAR="u,v,w">             <I PROPERTY="GlobalSysSoln" VALUE="IterativeStaticCond" />             <I PROPERTY="Preconditioner" VALUE="LowEnergyBlock"/>             <I PROPERTY="IterativeSolverTolerance"  VALUE="1e-8"/>           </V>           <V VAR="p">             <I PROPERTY="GlobalSysSoln" VALUE="IterativeStaticCond" />             <I PROPERTY="Preconditioner"  VALUE="FullLinearSpaceWithLowEnergyBlock"/>             <I PROPERTY="IterativeSolverTolerance"  VALUE="1e-7"/>           </V>        </GLOBALSYSSOLNINFO>

Everything works fine with TYPE="MODIFIED". Noteworthy, I tried TYPE="GLL_LAGRANGE_SEM" with the periodic pipe tutorial and it worked there, which is adding to my confusion! Could you kindly point out if something is wrong with my setup?

Kind regards syavash

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