What is tensor algebra in CFD?

Our Productive CFD course describes tensor algebra operations in equations of CFD

Productive CFD

2.24 Summary of tensor algebra

Below is tensor algebra applied to Cartesian (eqneqneqn) co-ordinates using: scalar eqn; vectors eqn, eqn; tensors eqn, eqn, eqn.

Products

  • Inner product of two vectors, Sec. 2.3
    s = a b = axbx + ayby + azbz \relax \special {t4ht=
  • Outer product of two vectors, Sec. 2.8
     0 1 axbx axby axbz T = ab = B@ aybx ayby aybz CA azbx azby azbz \relax \special {t4ht=
  • Inner product of vector and tensor, Sec. 2.6
     0 a T + a T + a T 1 B x xx y yx z zx C b = a T = @ axTxy + ayTyy + azTzy A axTxz + ayTyz + azTzz \relax \special {t4ht=
  • Inner product of two tensors, Sec. 2.8
    pict\relax \special {t4ht=
  • Double inner product of two tensors, Sec. 2.17
    s = T S = T S + T S + T S + xx xx xy xy xz xz TyxSyx + TyySyy + TyzSyz + TzxSzx + TzySzy + TzzSzz \relax \special {t4ht=
  • Cross product of two vectors, first used in Sec. 3.3 , produces a vector with components
    a b = (aybz azby;azbx axbz;axby aybx) \relax \special {t4ht=
    (2.70)

Tensors and operations

  • Transpose of a tensor, Sec. 2.7
     0 1 0 1 B Txx Txy Txz C T B Txx Tyx Tzx C T = @ Tyx Tyy Tyz A T = @ Txy Tyy Tzy A Tzx Tzy Tzz Txz Tyz Tzz \relax \special {t4ht=
  • Symmetric and skew tensors, Sec. 2.7
     1 1 T = -(T + TT) + -(T TT) = sym T + skw T 2|------------{z------------} |2------------{z------------} symmetric skew \relax \special {t4ht=
  • Trace of a tensor, Sec. 2.10
    tr(T) = T + T + T xx yy zz \relax \special {t4ht=
  • Identity tensor, Sec. 2.8
     0 1 B 1 0 0 C I = @ 0 1 0 A 0 0 1 I T T I T T sI str(T) \relax \special {t4ht=
  • Deviatoric and spherical tensors, Sec. 2.10
     1 1 T = T 3-(tr T)I + 3 (trT) I = devT + sph T |---------------{z---------------} |--------{z--------} deviatoric spherical \relax \special {t4ht=
Notes on CFD: General Principles - 2.24 Summary of tensor algebra