[BUG] Inconsistency in output of energy-momentum tensor

[xwgong01]

File

File: src/kernels/particle_moments.hpp
Module: kernel::ParticleMoments_kernel

Bug Description

The calculation of the stress-energy tensor moments (FldsID::T) in ParticleMoments_kernel contains inconsistent mass scaling factors across its different components, which leads to incorrect results.

According to the wikipage, the tensor Tij to be calculated by integrating of u^i u^j / u^0, which is the standard tensor normalized by m. However, the output in the code relates to the standard tensor T_std as follows:

• T00_code = T00_std

• T0i_code = T0i_std / m

• Tij_code = Tij_std / m^2

The problem is caused by line 166 of particle_moments.hpp, where the mass is included in the energy:

energy = mass * math::sqrt(ONE + NORM_SQR(u_Phys[0], u_Phys[1], u_Phys[2]));

Suggested Solution:

The mass should be removed from the expression.

[haykh]

Fixed with #152