.. _sec:probdescription:

Problem Description
===================


.. image:: ../figs/problem_description/vssuq_sketch.png
   :scale:  48
   :alt: sketch of the V S S U Q experimental setup


*  Geometry

   *  :math:`L_x =  38.09 \pm 0.02` (mm)
   *  :math:`L_y = 228.6` (mm)
   *  :math:`L_z =  38.11 \pm 0.02` (mm)

*  Bed mass

   *  :math:`M = 177.46 \pm 0.01` (g)
   *  :math:`M = 227.47 \pm 0.01` (g)

*  Inflow superficial velocity

   *  :math:`U = 1.83` (m/s)
   *  :math:`U = 1.99` (m/s)
   *  :math:`U = 2.13` (m/s)

*  Outflow conditions

   *  :math:`P_{atm} = 83.77` (kPa)
   *  :math:`T_{atm} = 293.15` (K)

*  Notes

   *  To clarify, there is only one bed mass and gas flow rate
      for a given run. The set of experimental conditions for which data was 
      collected and reported is listed in :ref:`sec:measurements`.
   *  The three flow conditions were set by flow meter readings of 3.6, 3.8 
      and 4.0 (SCFM) with back pressures of 12.5, 14 and 15 (psig),  
      respectively. See :ref:`sec:appxUcalc` for a discussion on the 
      calculation of :math:`U` and its uncertainty. 
   *  The distributor is a one-eighth inch thick disk, perforated 0.9 mm holes
      in a square grid with an edge size of 3.2 mm.
   *  The uncertainty in the atmospheric temperature is estimated to be
      approximately 5 (K). The uncertainty in the atmospheric pressure unknown.