From fc6fd82f61f72d359c1f6db8fd0f987e10880779 Mon Sep 17 00:00:00 2001 From: William Fullmer <william.fullmer@netl.doe.gov> Date: Wed, 13 Nov 2019 13:05:46 -0500 Subject: [PATCH] adding very short write up for QB case biseg --- docs/source/qb/biseg.rst | 34 ++++++++++++++++++++++++++++++-- docs/source/qb/granRT.rst | 12 +++++------ docs/source/qb/hcs.rst | 2 +- docs/source/qb/refs.rst | 4 ++++ docs/source/qb/single_bubble.rst | 2 +- 5 files changed, 44 insertions(+), 10 deletions(-) diff --git a/docs/source/qb/biseg.rst b/docs/source/qb/biseg.rst index 2c01430..9873497 100644 --- a/docs/source/qb/biseg.rst +++ b/docs/source/qb/biseg.rst @@ -3,8 +3,38 @@ Bidisperse Segregation ====================== -wdf TODO ASAP - +In this simple test conducted at NETL, a uniform, random mixture +of nylon +(:math:`d_p = 3.19` mm, :math:`\rho_p = 1130` kg/m\ :sup:`3` \) +and ceramic +(:math:`d_p = 4.25` mm, :math:`\rho_p = 2580` kg/m\ :sup:`3` \) +particles. When fluidized, the smaller, lighter nylon particles +(:math:`U_{mf} ~ 1.1` m/s) segregate out of the mixture to the top, +with the larger, heavier ceramic particles (:math:`U_{mf} ~ 1.8` m/s) +remaining at the bottom. The batch segregation test was conducted in +a small bed with a square cross-section of side length 60.325 mm. +Similar to previous observations of fluidized segregation of +bidisperse mixtures [GLMK03]_, the optimal separation was found to +occur just above the larger of the two minimum fluidization velocities. +Below the larger :math:`U_{mf}`, lack of fluidization inhibits particle +movement and too much above :math:`U_{mf}` vigorous bubbling promotes +mixture in the bed. + + +The optimal batch segregation experiment is simulated with MFiX-Exa 19.08 +discretized onto a :math:`8 \times 24 \times 8` mesh. No-slip walls are +set at vertical domain extents with a mass inflow and pressure outflow at +bottom and top, respectively. The :cpp:`Gidaspow` drag law is applied. +A defluidization curve of all ceramic particles was traced to find +:math:`U_{mf} \approx 1.9` m/s, close to the experimental value. The inflow +velocity is set to `2.0` m/s. The image below shows the simulated segregation +(inset) occurs much more rapidly than observed experimentally. In this case, +as the nylon particles begin to leave the mixture, the ceramic particles +defluidize. In the final state, the ceramic particles are essentially static +with a fluidized layer of nylon particles floating on top, in contrast to the +experiment, in which the full bed showed signs of fluidization. Investigation +into the over-segregation in this case is on-going. + .. figure:: figs/netl_biseg_1908_small.png :width: 16cm diff --git a/docs/source/qb/granRT.rst b/docs/source/qb/granRT.rst index 7846f18..f0ad225 100644 --- a/docs/source/qb/granRT.rst +++ b/docs/source/qb/granRT.rst @@ -43,12 +43,12 @@ The particles are assumed monodisperse with a constant diameter of :math:`d_p = 140` microns (:math:`dx^* \approx 1.8`) and density of :math:`\rho_p = 1050` kg/m\ :sup:`3` \. The resitution and sliding friction coefficients are set to 0.9 and 0.25, which are believed to be representative -of the polystyrene material. The Wen and Yu drag law [WY66]_ is applied. -1.12M particles are initially randomly distributed throughout the domain. -The gravity force on the particles is modified by :math:`\tanh 100(t - 2)` -so that the particles initially settle upwards, and then the body force is -quickly inverted around :math:`t = 2` s, causing the particles to fall -downward into the quiescent air. +of the polystyrene material. The :cpp:`WenYu` drag law of Wen and Yu drag +[WY66]_ is applied. 1.12M particles are initially randomly distributed +throughout the domain. The gravity force on the particles is modified by +:math:`\tanh 100(t - 2)` so that the particles initially settle upwards, +and then the body force is quickly inverted around :math:`t = 2` s, +causing the particles to fall downward into the quiescent air. .. figure:: figs/granRT_1908_small.png diff --git a/docs/source/qb/hcs.rst b/docs/source/qb/hcs.rst index 59332ca..4c43d9e 100644 --- a/docs/source/qb/hcs.rst +++ b/docs/source/qb/hcs.rst @@ -47,7 +47,7 @@ In order to avoid the region near critical stability, we use a significnatly larger system size: :math:`L^*_x = L^*_y = 256`. The system is thin in the depth dimension, :math:`L^*_z = 8` in order to highlight the clustering phenomena. Therefore, :math:`N_p = 50000`. Because the system is hypothetical, -the ideal ``BVK2`` DNS drag law is applied, see [BvK07]_, [TPKKv15]_. +the ideal :cpp:`BVK2` DNS drag law is applied, see [BvK07]_, [TPKKv15]_. .. figure:: figs/hcs_ke_1908.png diff --git a/docs/source/qb/refs.rst b/docs/source/qb/refs.rst index 4631791..fb7b68b 100644 --- a/docs/source/qb/refs.rst +++ b/docs/source/qb/refs.rst @@ -7,6 +7,10 @@ References Kuipers. Drag force of intermediate Reynolds number flow past mono- and bidisperse arrays of spheres. *AIChE Journal*, **53**, 489--501 (2007). +.. [GLMK03] M.J.V. Goldschmidt, J.M. Link, S. Mellema, and J.A.M. Kuipers. + Digital image analysis measurements of bed expansion and segregation dynamics + in dense gas-fluidised beds. *Powder Technology*, **138** (2-3), 135--159 (2003). + .. [BPLPM19] C.M. Boyce, A. Penn, M. Lehnert, K.P. Pruessmann, and C.R. Müller. Magnetic resonance imaging of single bubbles injected into incipiently fluidized beds. *Chemical Engineering Science*, **200**, 147--166 (2019). diff --git a/docs/source/qb/single_bubble.rst b/docs/source/qb/single_bubble.rst index 3f62e5a..4e37890 100644 --- a/docs/source/qb/single_bubble.rst +++ b/docs/source/qb/single_bubble.rst @@ -37,7 +37,7 @@ applied in all cases. A separate defluidization simulation was first carried out first to determine -:math:`U_{mf} \approx 0.66` m/s using the `WenYu` [WY66]_ drag law, slightly +:math:`U_{mf} \approx 0.66` m/s using the :cpp:`WenYu` [WY66]_ drag law, slightly below the experimentally measured value of :math:`U_{mf} = 0.7` m/s. The bed was prepared with two initialization simulations. First, the particle initial condition is fluidized above :math:`U_{mf}` at :math:`0.8` m/s for one second -- GitLab