  We formulate the next-to-leading order nuclear effective field theory without
pions in the two-nucleon sector on a spatial lattice, and investigate
nonperturbative renormalization group flows in the strong coupling region by
diagonalizing the Hamiltonian numerically. The cutoff (proportional to the
inverse of the lattice constant) dependence of the coupling constants is
obtained by changing the lattice constant with the binding energy and the
asymptotic normalization constant for the groundstate being fixed. We argue
that the critical line can be obtained by looking at the finite-size dependence
of the groundstate energy. We determine the relevant operator and locate the
nontrivial fixed point, as well as the physical flow line corresponding to the
deuteron in the two-dimensional plane of dimensionless coupling constants. It
turns out that the location of the nontrivial fixed point is very close to the
one obtained by the corresponding analytic calculation, but the relevant
operator is quite different.
