Navier-Stokes-Boussinsq equations in a tube; estimates when the data is front-like

For the solutions of Navier-Stokes-Boussinesq equations in a three-dimensional thin tube with front like initial data, we derive some uniform estimates on the burning rate and the flow velocity, which can be interpreted as stability results for the laminar front. We also show that the front-like datum admits a solution which will stay front-like in time. We consider no-slip (Dirichlet) boundary condition for the flow, and no-flux (Neumann) boundary condition for the reactant(temperature).