We construct an explicitly anisotropic nucleonic mean field, for a phase-space density anisotropic in momentum, convenient for modeling of nuclear reactions, using separable interactions in momentum space. We demonstrate the flexibility of our separable model for the potential energy density V associated with the momentum-dependent mean field U, by approximating the respective expressions by Welke et al. which also serve as reference. Therefore, we apply an expansion in spherical harmonics, comprising scalar and tensorial terms to Welke's potential energy density, laying open the anisotropy of the mean field. Ground-state properties in the reference model can be well described within our framework. The anisotropy in our model is parameterized by relying on anisotropic Gaussian distributions for excited-matter scenarios. We show that the strongly anisotropic mean field of 2 Fermi spheres in momentum space can be reproduced within our framework. As for the contribution to the velocity field deduced from our mean field parameterization, we find that for large anisotropies particle velocities tend to be weakly directed along the transverse momentum axis. Our parameterization can be applied in BUU transport simulations with gain over an approach of the type of Welke et al. in reduced computational cost and reduced error-proneness.
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