19-10-2012, 11:40 AM
Lemkin sees what he wants to see and fails to see what actually occurred. There was no pyroclastic flow. ... a complete misnomer and an attempt it appears at a sort of shock and awe.
The concrete and other friable materials were reduced through collisions, abrasion, grinding to dust and small sizes particles. There was no stone in the concrete aggregate and the concrete was light weight and there were only a few areas with re bar. It was more like a poured gypsum wall board into thin fluted metal pans (22 gauge -.033" thk). It broke apart very easily. it was NOT structural concrete that one knows of from side walks, retaining walls and basement floors even. The aggregate used was likely extremely lightweight ground slag or fly ash with little ability to hold the composite together... certainly less than stone aggregate which gives concrete strength.
The heat released from the fiction was transferred to the building materials, crushed concrete and broken steel and in turn to the surround air. It represented a heat sink of almost 400,000 tons for each tower. No matter was destroyed.. a bit combusted and turned to gas and smoke which drifted off the the SE. But most of the destroyed materials are seen coming down from gravity of course close to the building. Heavy steel of the facade can be seen falling away... some core steel which survived the core collapse at tall as 50 stories toppled over or self buckled. The compacted volume of the concrete were it stacked one floor atop the other would be not even 34 feet high. The pour was 4" max and the flutes were 1 1/2" deep so at least half the slabs thickness was only 2 1/2".
The elevated heat of the debris from friction heated the air above it by radiation heat transfer. The collapse itself also *pulled* a low pressure zone behind (above) it as any moving thing does... air rushes in to fill the volume the moving object once occupied. In the case of the building collapse this represented a mass of air equal to the volume of the towers... with each floor representing 18,000, cubic yards of air that was replaced at 1 *floor" per second... or about 65 mph of down draft (the measured speed of collapse which was about 15 seconds). The is analgous to water rushing down a sink drain when the stopper is pulled out. Or fill a tube with sand which is standing on a table and lift the tube and the sands rushes out the bottom and air comes in to the top of the tube (down draft) at the speed that the sand leaves it from the bottom.
So you had heated debris with hundreds of thousands of tons of dust facing a down draft of 65 mph of cooler air. The down draft air was heated... as cool air from a bellows would be heated when encountering hot materials. This interaction caused the down draft air to spread radially from the base of the former tower where the hot debris was piled up. The lighter debris and dust was swept up in the moving air.
Hot air expands as Boyle's gas laws explain and so the dust laddened air billowed up and was seen as enormous dust clouds and faster moving air rushed outward in all directions carrying dust and even heavier particles. The down draft of air can be understood of one takes a hose of pressurized water or air and directs it downward at a pile of broken up ash and hot embers. The force of the downward fluid will hit the pile of hot ash and embers and disburse them in all directions and the air will carry with it some of the heat of the smoldering fire.
If a burning building were to collapse, a pulse of hot air would radiate from the collapse. In this case the pulse was driven by the down draft which received heat from the heated debris and remains of the building.
So whatever the cause of the heating of the debris... the production of the huge billowing dust clouds and the rush of hot dust filled air from the site of the collapse is explained by Boyle's, Charle's , Avogadro's and other fundamental gas laws known for centuries. Itwas not a pyroclastic flow.
The was no slope or gradient or gravity driving the pulse of hot gas (wind). It was driven by the down draft.
Why not describe what actually caused the wind pulse and hot cloulds with emerged post collapse? The did occur in both the top down driven floor collapse of the twin towers and the bottom driven structural collapse of WTC 7. Both produced similar outcomes of hot debris filled wind pulses and dust laddened billowing clouds. Because Boyle's gas laws... the *laws of physics* describe what happened.
The concrete and other friable materials were reduced through collisions, abrasion, grinding to dust and small sizes particles. There was no stone in the concrete aggregate and the concrete was light weight and there were only a few areas with re bar. It was more like a poured gypsum wall board into thin fluted metal pans (22 gauge -.033" thk). It broke apart very easily. it was NOT structural concrete that one knows of from side walks, retaining walls and basement floors even. The aggregate used was likely extremely lightweight ground slag or fly ash with little ability to hold the composite together... certainly less than stone aggregate which gives concrete strength.
The heat released from the fiction was transferred to the building materials, crushed concrete and broken steel and in turn to the surround air. It represented a heat sink of almost 400,000 tons for each tower. No matter was destroyed.. a bit combusted and turned to gas and smoke which drifted off the the SE. But most of the destroyed materials are seen coming down from gravity of course close to the building. Heavy steel of the facade can be seen falling away... some core steel which survived the core collapse at tall as 50 stories toppled over or self buckled. The compacted volume of the concrete were it stacked one floor atop the other would be not even 34 feet high. The pour was 4" max and the flutes were 1 1/2" deep so at least half the slabs thickness was only 2 1/2".
The elevated heat of the debris from friction heated the air above it by radiation heat transfer. The collapse itself also *pulled* a low pressure zone behind (above) it as any moving thing does... air rushes in to fill the volume the moving object once occupied. In the case of the building collapse this represented a mass of air equal to the volume of the towers... with each floor representing 18,000, cubic yards of air that was replaced at 1 *floor" per second... or about 65 mph of down draft (the measured speed of collapse which was about 15 seconds). The is analgous to water rushing down a sink drain when the stopper is pulled out. Or fill a tube with sand which is standing on a table and lift the tube and the sands rushes out the bottom and air comes in to the top of the tube (down draft) at the speed that the sand leaves it from the bottom.
So you had heated debris with hundreds of thousands of tons of dust facing a down draft of 65 mph of cooler air. The down draft air was heated... as cool air from a bellows would be heated when encountering hot materials. This interaction caused the down draft air to spread radially from the base of the former tower where the hot debris was piled up. The lighter debris and dust was swept up in the moving air.
Hot air expands as Boyle's gas laws explain and so the dust laddened air billowed up and was seen as enormous dust clouds and faster moving air rushed outward in all directions carrying dust and even heavier particles. The down draft of air can be understood of one takes a hose of pressurized water or air and directs it downward at a pile of broken up ash and hot embers. The force of the downward fluid will hit the pile of hot ash and embers and disburse them in all directions and the air will carry with it some of the heat of the smoldering fire.
If a burning building were to collapse, a pulse of hot air would radiate from the collapse. In this case the pulse was driven by the down draft which received heat from the heated debris and remains of the building.
So whatever the cause of the heating of the debris... the production of the huge billowing dust clouds and the rush of hot dust filled air from the site of the collapse is explained by Boyle's, Charle's , Avogadro's and other fundamental gas laws known for centuries. Itwas not a pyroclastic flow.
"A pyroclastic flow (also known scientifically as a pyroclastic density current[SUP][1][/SUP]) is a fast-moving current of superheated gas and rock (collectively known as tephra), which reaches speeds moving away from a volcano of up to 700 km/h (450 mph).[SUP][2][/SUP] The gas can reach temperatures of about 1,000 °C (1,830 °F). Pyroclastic flows normally hug the ground and travel downhill, or spread laterally under gravity. Their speed depends upon the density of the current, the volcanic output rate, and the gradient of the slope. They are a common and devastating result of certain explosive volcanic eruptions."
The was no slope or gradient or gravity driving the pulse of hot gas (wind). It was driven by the down draft.
Why not describe what actually caused the wind pulse and hot cloulds with emerged post collapse? The did occur in both the top down driven floor collapse of the twin towers and the bottom driven structural collapse of WTC 7. Both produced similar outcomes of hot debris filled wind pulses and dust laddened billowing clouds. Because Boyle's gas laws... the *laws of physics* describe what happened.