CERN-LHC. The second-order Fourier coefficients ($v_{2}$) characterizing the azimuthal distribution of $\Upsilon(\mathrm{1S})$ and $\Upsilon(\mathrm{2S})$ mesons arising from PbPb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV are studied. The $\Upsilon$ mesons are reconstructed in their $\mathrm{dimuon}$ decay channel, as measured by the CMS detector. The data set was collected in 2018 and corresponds to an integrated luminosity of 1.7$\smash{\,\text{nb}^{-1}}$. The scalar product method is used to extract the $v_{2}$ coefficients of the azimuthal distribution. Results are reported for the rapidity range $|y|<2.4$, with the transverse momentum $0 < $ ${p_{\mathrm{T}}}$ $ < 50\smash{\,\text{GeV/c}}$, and in three centrality ranges of 10-30, 30-50 and 50-90%. In contrast to the J/$\psi$ mesons, no azimuthal anisotropy is observed for the $\Upsilon$ mesons.