Dense (particle dominated) Transport

• name four examples of dense particle dominated flows?

  lahars, mudflows, debris flows and rock falls
• where did the term lahar come from?

  indonesia
• what is a lahar?

  a mixture of volcanic material with water
• when do lahars occur?

  when there is a lake or glacier on top of a volcano
• what is the structure of a dense particle flow?

  • fine small particles moving on top like a sand storm
  • bigger particles like a mud flow beneath
  • large rocks and huge material at the bottom
  • a dense flow with the largest particles moving in circular motions at the nose
• what can we use to classify dense particle dominated flows?

  the total percentage of solids in the flow and within that amount, what fraction of that is solid
• when can we call it a debris flow?

  when the material is more than 50% sand sized particles
• what are landslides?

  one coherent block of solid material moving down slope
• what are debris flows?

  a mass movement of loose particles
• what is the difference between a rock fall and a debris flow?

  a debris flow can other content other than just rock (eg: water), whereas rock falls are entirely rock
• what is the branch of physicals regarding the flow of matters called?

  rheology
• what are the two approaches to studying dense flows?

  considering the entire mass as one fluid or considering the water and coarser material separately - this is called the grain-flow model
• what are the four forces in the grain-flow model?

  collisional, frictional, viscous and pore pressure