Simulations　of　free　convective　heat　transfer　(HT)　and　entropy　generation　(S-Gen)　in　a　closed　enclosure　are　carried　out　in　this　research.　T-c　is　the　temperature　of　the　enclosure＇s　top　circular　wall.　A　piece　of　the　enclosure＇s　left　wall　(L)　and　a　section　of　the　enclosure＇s　right　wall　(H)　are　both　at　T-h.　The　remainder　of　the　walls　are　insulated.　A　constant　volumetric　radiation　(R-d)　is　produced　within　the　cavity.　In　relation　to　the　horizon,　the　enclosure　is　at　45　degrees　angle.　The　equations　are　solved　using　the　lattice　Boltzmann　method　(LBM).　The　thermal　conductivity　of　nanofluids　(NFs)　was　also　calculated　using　a　model　based　on　empirical　data.　The　following　findings　are　obtained　by　varying　the　Ha,　the　length　of　the　heated　walls,　and　the　angle　of　the　magnetic　field　(MaF).　An　increase　in　Ha　lowers　the　quantity　of　Nu　on　both　heated　walls　and　weakens　the　fluid　flow　in　the　enclosure.　The　HT　rate　is　increased　by　increasing　the　length　of　heated　walls.　The　quantity　of　HT　from　hot　walls　varies　depending　on　the　angle　of　the　MaF.　The　quantity　of　HT　from　one　of　the　hot　walls　may　be　larger　depending　on　the　angle　of　the　MaF.　An　increment　in　the　angle　of　the　magnetic　field　from　0　to　60　degrees　enhances　the　Nusselt　number　by　10.3%.