[tbao]

Dear all,

I am using soildDisplacementFoam to implement ModifiledCamClay model. For this purpose, I need to calculate eigenvalues and eigenvectors using the utility preimplemented in OF, i.e., eigenValues(sigma[celli]) and eigenVectors(sigma[celli]). However, I will always have problems like this for some cells: complex eigenvalues detected for symmTensor. Due to this problem, calculated eigenvalues are set up to zero. Here is the log file with this problem:

part 1:

sigma_previous= (-150000 0 0 -150000 0 -150000) end
sigmaD= (-22.715 0.268961 -0.0164544 -17.9137 0.0715722 -18.7927) end
sigma[celli]= (-150023 0.268961 -0.0164544 -150018 0.0715722 -150019) end
eigenValues== (-150023 -150019 -150018) end
eigenVectors[]s= (0.998372 -0.0567947 0.00531486 -0.00883938 -0.0566245 0.998356 0.0526201 0.996743 0.0611068) end
yield[celli]= 2.97148e+06 end
pc_stress[celli]= -150000 end
p_stress[celli]= -150020 end
q_stress[celli]= 4.454 end

part 2:

sigma_previous= (-150000 0 0 -150000 0 -150000) end
sigmaD= (-22.7003 0.268504 -0.00720373 -17.8241 0.0178865 -18.8122) end
sigma[celli]= (-150023 0.268504 -0.00720373 -150018 0.0178865 -150019) end
--> FOAM Warning :
From function eigenValues(const symmTensor&)
in file primitives/Tensor/tensor/tensor.C at line 370
complex eigenvalues detected for symmTensor: (-150023 0.268504 -0.00720373 -150018 0.0178865 -150019)
eigenValues== (0 0 0) end
--> FOAM Warning :
From function eigenValues(const symmTensor&)
in file primitives/Tensor/tensor/tensor.C at line 370
complex eigenvalues detected for symmTensor: (-150023 0.268504 -0.00720373 -150018 0.0178865 -150019)
eigenVectors[]s= (0 0 0 0 0 0 0 0 0) end
--> FOAM Warning :
From function eigenValues(const symmTensor&)
in file primitives/Tensor/tensor/tensor.C at line 370
complex eigenvalues detected for symmTensor: (-150023 0.268504 -0.00720373 -150018 0.0178865 -150019)
--> FOAM Warning :
From function eigenValues(const symmTensor&)
in file primitives/Tensor/tensor/tensor.C at line 370
complex eigenvalues detected for symmTensor: (-150023 0.268504 -0.00720373 -150018 0.0178865 -150019)
--> FOAM Warning :
From function eigenValues(const symmTensor&)
in file primitives/Tensor/tensor/tensor.C at line 370
complex eigenvalues detected for symmTensor: (-150023 0.268504 -0.00720373 -150018 0.0178865 -150019)
--> FOAM Warning :
From function eigenValues(const symmTensor&)
in file primitives/Tensor/tensor/tensor.C at line 370
complex eigenvalues detected for symmTensor: (-150023 0.268504 -0.00720373 -150018 0.0178865 -150019)
--> FOAM Warning :
From function eigenValues(const symmTensor&)
in file primitives/Tensor/tensor/tensor.C at line 370
complex eigenvalues detected for symmTensor: (-150023 0.268504 -0.00720373 -150018 0.0178865 -150019)
--> FOAM Warning :
From function eigenValues(const symmTensor&)
in file primitives/Tensor/tensor/tensor.C at line 370
complex eigenvalues detected for symmTensor: (-150023 0.268504 -0.00720373 -150018 0.0178865 -150019)
--> FOAM Warning :
From function eigenValues(const symmTensor&)
in file primitives/Tensor/tensor/tensor.C at line 370
complex eigenvalues detected for symmTensor: (-150023 0.268504 -0.00720373 -150018 0.0178865 -150019)
--> FOAM Warning :
From function eigenValues(const symmTensor&)
in file primitives/Tensor/tensor/tensor.C at line 370
complex eigenvalues detected for symmTensor: (-150023 0.268504 -0.00720373 -150018 0.0178865 -150019)
--> FOAM Warning :
From function eigenValues(const symmTensor&)
in file primitives/Tensor/tensor/tensor.C at line 370
complex eigenvalues detected for symmTensor: (-150023 0.268504 -0.00720373 -150018 0.0178865 -150019)

As you can see, for part 1, it is correct, however, for part 2, I have the issue. I calculate eigenvalues for this matrix using matlab, it will not give any errors. Instead, Matlab gives me real eigenvalues. I have searched forum to find out answers for this issue. It seems that nobody has solved this problem. Therefore, I started this thread.

I simulated a cylindrical soil, which has three patches, top, surrounding, and bottom. If I use fixedvalue for D (displacement) at the top and bottom, tractiondisplacement for the surrounding, it will not give that error. However, if I use tractiondisplacement for top or bottom, I will have this error.

I appreciate if anybody can help me figure it out. Is this one related to boundary conditions or anything else? Thanks in advance.