def sim_flow_constraint_rule(mod, g, tmp):
    """
    **Constraint Name**: Sim_Flow_Constraint
    **Enforced Over**: SIM_FLOW_LMT_TMPS

    Total flow on lines in each simultaneous flow group cannot exceed limit.
    """
    return mod.Sim_Flow_MW[g, tmp] \
        <= mod.sim_flow_lmt_mw[g, mod.period[tmp]]