Mathematicians who research PDE and Analysis for fluid dynamics problems vs. Applied Mathematicians who conduct experiments, model and simulate

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I'm close to the modeling, simulation, and experimental work in fluid dynamics, but I've been wondering about mathematicians that do analysis and PDEs: for example, what do physical quantities such as the viscosity mean to the mathematicians? In modeling, simulations and experiments, there's a great deal of focus on physical intuition -- one would describe the quantities physically, e.g. describe physically the drag or lift force, the viscosity, the torque, etc. For someone in analysis and PDEs, is it necessary for them to have the same level of physical intuition, or is something such as the viscosity simply viewed as an input, a number, to the mathematician?



I guess generally I am wondering whether mathematicians that work in analysis and pdes have to know any physics at all - is a yes / no answer possible here?



(In a math department, I've often seen many grad-level topics courses in PDEs and fluid dynamics that specify "no physics background is assumed". The requirements were mathematical, e.g. real analysis, functional analysis, and harmonic analysis.)



Thanks







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    Relevant Feynman quote: "Anyone who wants to analyze the properties of matter in a real problem might want to start by writing down the fundamental equations and then try to solve them mathematically. Although there are people who try to use such an approach, these people are the failures in this field; the real successes come to those who start from a physical point of view, people who have a rough idea where they are going and then begin by making the right kind of approximations, knowing what is big and what is small in a given complicated situation."
    – littleO
    Jul 21 at 4:56















up vote
4
down vote

favorite
2












I'm close to the modeling, simulation, and experimental work in fluid dynamics, but I've been wondering about mathematicians that do analysis and PDEs: for example, what do physical quantities such as the viscosity mean to the mathematicians? In modeling, simulations and experiments, there's a great deal of focus on physical intuition -- one would describe the quantities physically, e.g. describe physically the drag or lift force, the viscosity, the torque, etc. For someone in analysis and PDEs, is it necessary for them to have the same level of physical intuition, or is something such as the viscosity simply viewed as an input, a number, to the mathematician?



I guess generally I am wondering whether mathematicians that work in analysis and pdes have to know any physics at all - is a yes / no answer possible here?



(In a math department, I've often seen many grad-level topics courses in PDEs and fluid dynamics that specify "no physics background is assumed". The requirements were mathematical, e.g. real analysis, functional analysis, and harmonic analysis.)



Thanks







share|cite|improve this question

















  • 9




    Relevant Feynman quote: "Anyone who wants to analyze the properties of matter in a real problem might want to start by writing down the fundamental equations and then try to solve them mathematically. Although there are people who try to use such an approach, these people are the failures in this field; the real successes come to those who start from a physical point of view, people who have a rough idea where they are going and then begin by making the right kind of approximations, knowing what is big and what is small in a given complicated situation."
    – littleO
    Jul 21 at 4:56













up vote
4
down vote

favorite
2









up vote
4
down vote

favorite
2






2





I'm close to the modeling, simulation, and experimental work in fluid dynamics, but I've been wondering about mathematicians that do analysis and PDEs: for example, what do physical quantities such as the viscosity mean to the mathematicians? In modeling, simulations and experiments, there's a great deal of focus on physical intuition -- one would describe the quantities physically, e.g. describe physically the drag or lift force, the viscosity, the torque, etc. For someone in analysis and PDEs, is it necessary for them to have the same level of physical intuition, or is something such as the viscosity simply viewed as an input, a number, to the mathematician?



I guess generally I am wondering whether mathematicians that work in analysis and pdes have to know any physics at all - is a yes / no answer possible here?



(In a math department, I've often seen many grad-level topics courses in PDEs and fluid dynamics that specify "no physics background is assumed". The requirements were mathematical, e.g. real analysis, functional analysis, and harmonic analysis.)



Thanks







share|cite|improve this question













I'm close to the modeling, simulation, and experimental work in fluid dynamics, but I've been wondering about mathematicians that do analysis and PDEs: for example, what do physical quantities such as the viscosity mean to the mathematicians? In modeling, simulations and experiments, there's a great deal of focus on physical intuition -- one would describe the quantities physically, e.g. describe physically the drag or lift force, the viscosity, the torque, etc. For someone in analysis and PDEs, is it necessary for them to have the same level of physical intuition, or is something such as the viscosity simply viewed as an input, a number, to the mathematician?



I guess generally I am wondering whether mathematicians that work in analysis and pdes have to know any physics at all - is a yes / no answer possible here?



(In a math department, I've often seen many grad-level topics courses in PDEs and fluid dynamics that specify "no physics background is assumed". The requirements were mathematical, e.g. real analysis, functional analysis, and harmonic analysis.)



Thanks









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edited Jul 29 at 19:28









DisintegratingByParts

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asked Jul 21 at 4:44









Jalapeno Nachos

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  • 9




    Relevant Feynman quote: "Anyone who wants to analyze the properties of matter in a real problem might want to start by writing down the fundamental equations and then try to solve them mathematically. Although there are people who try to use such an approach, these people are the failures in this field; the real successes come to those who start from a physical point of view, people who have a rough idea where they are going and then begin by making the right kind of approximations, knowing what is big and what is small in a given complicated situation."
    – littleO
    Jul 21 at 4:56













  • 9




    Relevant Feynman quote: "Anyone who wants to analyze the properties of matter in a real problem might want to start by writing down the fundamental equations and then try to solve them mathematically. Although there are people who try to use such an approach, these people are the failures in this field; the real successes come to those who start from a physical point of view, people who have a rough idea where they are going and then begin by making the right kind of approximations, knowing what is big and what is small in a given complicated situation."
    – littleO
    Jul 21 at 4:56








9




9




Relevant Feynman quote: "Anyone who wants to analyze the properties of matter in a real problem might want to start by writing down the fundamental equations and then try to solve them mathematically. Although there are people who try to use such an approach, these people are the failures in this field; the real successes come to those who start from a physical point of view, people who have a rough idea where they are going and then begin by making the right kind of approximations, knowing what is big and what is small in a given complicated situation."
– littleO
Jul 21 at 4:56





Relevant Feynman quote: "Anyone who wants to analyze the properties of matter in a real problem might want to start by writing down the fundamental equations and then try to solve them mathematically. Although there are people who try to use such an approach, these people are the failures in this field; the real successes come to those who start from a physical point of view, people who have a rough idea where they are going and then begin by making the right kind of approximations, knowing what is big and what is small in a given complicated situation."
– littleO
Jul 21 at 4:56











2 Answers
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I guess I can chime in on my current experience. I am a current undergraduate at University of California, Los Angeles that is doing research on fluid dynamics in the Math Department (with a higher emphasis in the Applied Portion); in particular, on inertial flow in microfluidic devices.



I have also taken a graduate course in the math department on Fluid Dynamics in the Math Department. In my line of research, we mainly focus on the incompressible Navier Stokes e.g. we assume $nabla cdot textbfu = 0$, where $textbfu $ is the fluid velocity. Then we have the following equation beginalign mu nabla^2 textbfu - nabla p = rho(fracpartial textbfupartial t + textbfu cdot nabla textbfu) endalign
beginalign nabla cdot textbfu = 0endalign where we assumed our forces are negligible, and that the viscosity $mu$ and density $rho$ are constants. With these assumptions, we can non-dimensionalize the Navier Stokes Equation to obtain beginalignnabla^2 textbfu - nabla p = Re(fracpartial textbfupartial t + textbfu cdot nabla textbfu) endalign with $Re$ being a dimensionless constant known as the Reynolds Number.



This is very powerful as this allows us to reduce the physical intuition needed to understand the equations. Indeed, in the dimensionless formulation, we can view the Reynolds Number as the balancing term between the viscous and pressure terms compared to the inertial terms.



We use mainly analytical tools such as asymptotic expansion, dominant balance, numerical solvers, and the weak formulation of the incompressible dimensionless Navier Stokes to approximate the flow. E.g., we don't use many physical properties about the fluid. Even in my graduate course, the only physics we really used were deriving the Navier Stokes equation.



However, I'm sure there are many more sophisticated tools from analysis that one can use to study these PDEs in much more detail, but I have only taken up to Measure Theory and a basic introduction to PDE course. But, I hope this answers sheds some light on how mathematicians view Fluid Mechanics.



For reference on the physics question, I have not taken any physics since high school physics so far. Sometimes it's a struggle to understand the underlying physics, but it is at an accessible level who puts in the effort.






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    Well, yes. Most (if not all) good mathematical arguments are a rigorous representation of physical intuition. And that is their power: the justification of this intuition via rigorous arguments on a formal basis.






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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes








      up vote
      6
      down vote



      accepted










      I guess I can chime in on my current experience. I am a current undergraduate at University of California, Los Angeles that is doing research on fluid dynamics in the Math Department (with a higher emphasis in the Applied Portion); in particular, on inertial flow in microfluidic devices.



      I have also taken a graduate course in the math department on Fluid Dynamics in the Math Department. In my line of research, we mainly focus on the incompressible Navier Stokes e.g. we assume $nabla cdot textbfu = 0$, where $textbfu $ is the fluid velocity. Then we have the following equation beginalign mu nabla^2 textbfu - nabla p = rho(fracpartial textbfupartial t + textbfu cdot nabla textbfu) endalign
      beginalign nabla cdot textbfu = 0endalign where we assumed our forces are negligible, and that the viscosity $mu$ and density $rho$ are constants. With these assumptions, we can non-dimensionalize the Navier Stokes Equation to obtain beginalignnabla^2 textbfu - nabla p = Re(fracpartial textbfupartial t + textbfu cdot nabla textbfu) endalign with $Re$ being a dimensionless constant known as the Reynolds Number.



      This is very powerful as this allows us to reduce the physical intuition needed to understand the equations. Indeed, in the dimensionless formulation, we can view the Reynolds Number as the balancing term between the viscous and pressure terms compared to the inertial terms.



      We use mainly analytical tools such as asymptotic expansion, dominant balance, numerical solvers, and the weak formulation of the incompressible dimensionless Navier Stokes to approximate the flow. E.g., we don't use many physical properties about the fluid. Even in my graduate course, the only physics we really used were deriving the Navier Stokes equation.



      However, I'm sure there are many more sophisticated tools from analysis that one can use to study these PDEs in much more detail, but I have only taken up to Measure Theory and a basic introduction to PDE course. But, I hope this answers sheds some light on how mathematicians view Fluid Mechanics.



      For reference on the physics question, I have not taken any physics since high school physics so far. Sometimes it's a struggle to understand the underlying physics, but it is at an accessible level who puts in the effort.






      share|cite|improve this answer



























        up vote
        6
        down vote



        accepted










        I guess I can chime in on my current experience. I am a current undergraduate at University of California, Los Angeles that is doing research on fluid dynamics in the Math Department (with a higher emphasis in the Applied Portion); in particular, on inertial flow in microfluidic devices.



        I have also taken a graduate course in the math department on Fluid Dynamics in the Math Department. In my line of research, we mainly focus on the incompressible Navier Stokes e.g. we assume $nabla cdot textbfu = 0$, where $textbfu $ is the fluid velocity. Then we have the following equation beginalign mu nabla^2 textbfu - nabla p = rho(fracpartial textbfupartial t + textbfu cdot nabla textbfu) endalign
        beginalign nabla cdot textbfu = 0endalign where we assumed our forces are negligible, and that the viscosity $mu$ and density $rho$ are constants. With these assumptions, we can non-dimensionalize the Navier Stokes Equation to obtain beginalignnabla^2 textbfu - nabla p = Re(fracpartial textbfupartial t + textbfu cdot nabla textbfu) endalign with $Re$ being a dimensionless constant known as the Reynolds Number.



        This is very powerful as this allows us to reduce the physical intuition needed to understand the equations. Indeed, in the dimensionless formulation, we can view the Reynolds Number as the balancing term between the viscous and pressure terms compared to the inertial terms.



        We use mainly analytical tools such as asymptotic expansion, dominant balance, numerical solvers, and the weak formulation of the incompressible dimensionless Navier Stokes to approximate the flow. E.g., we don't use many physical properties about the fluid. Even in my graduate course, the only physics we really used were deriving the Navier Stokes equation.



        However, I'm sure there are many more sophisticated tools from analysis that one can use to study these PDEs in much more detail, but I have only taken up to Measure Theory and a basic introduction to PDE course. But, I hope this answers sheds some light on how mathematicians view Fluid Mechanics.



        For reference on the physics question, I have not taken any physics since high school physics so far. Sometimes it's a struggle to understand the underlying physics, but it is at an accessible level who puts in the effort.






        share|cite|improve this answer

























          up vote
          6
          down vote



          accepted







          up vote
          6
          down vote



          accepted






          I guess I can chime in on my current experience. I am a current undergraduate at University of California, Los Angeles that is doing research on fluid dynamics in the Math Department (with a higher emphasis in the Applied Portion); in particular, on inertial flow in microfluidic devices.



          I have also taken a graduate course in the math department on Fluid Dynamics in the Math Department. In my line of research, we mainly focus on the incompressible Navier Stokes e.g. we assume $nabla cdot textbfu = 0$, where $textbfu $ is the fluid velocity. Then we have the following equation beginalign mu nabla^2 textbfu - nabla p = rho(fracpartial textbfupartial t + textbfu cdot nabla textbfu) endalign
          beginalign nabla cdot textbfu = 0endalign where we assumed our forces are negligible, and that the viscosity $mu$ and density $rho$ are constants. With these assumptions, we can non-dimensionalize the Navier Stokes Equation to obtain beginalignnabla^2 textbfu - nabla p = Re(fracpartial textbfupartial t + textbfu cdot nabla textbfu) endalign with $Re$ being a dimensionless constant known as the Reynolds Number.



          This is very powerful as this allows us to reduce the physical intuition needed to understand the equations. Indeed, in the dimensionless formulation, we can view the Reynolds Number as the balancing term between the viscous and pressure terms compared to the inertial terms.



          We use mainly analytical tools such as asymptotic expansion, dominant balance, numerical solvers, and the weak formulation of the incompressible dimensionless Navier Stokes to approximate the flow. E.g., we don't use many physical properties about the fluid. Even in my graduate course, the only physics we really used were deriving the Navier Stokes equation.



          However, I'm sure there are many more sophisticated tools from analysis that one can use to study these PDEs in much more detail, but I have only taken up to Measure Theory and a basic introduction to PDE course. But, I hope this answers sheds some light on how mathematicians view Fluid Mechanics.



          For reference on the physics question, I have not taken any physics since high school physics so far. Sometimes it's a struggle to understand the underlying physics, but it is at an accessible level who puts in the effort.






          share|cite|improve this answer















          I guess I can chime in on my current experience. I am a current undergraduate at University of California, Los Angeles that is doing research on fluid dynamics in the Math Department (with a higher emphasis in the Applied Portion); in particular, on inertial flow in microfluidic devices.



          I have also taken a graduate course in the math department on Fluid Dynamics in the Math Department. In my line of research, we mainly focus on the incompressible Navier Stokes e.g. we assume $nabla cdot textbfu = 0$, where $textbfu $ is the fluid velocity. Then we have the following equation beginalign mu nabla^2 textbfu - nabla p = rho(fracpartial textbfupartial t + textbfu cdot nabla textbfu) endalign
          beginalign nabla cdot textbfu = 0endalign where we assumed our forces are negligible, and that the viscosity $mu$ and density $rho$ are constants. With these assumptions, we can non-dimensionalize the Navier Stokes Equation to obtain beginalignnabla^2 textbfu - nabla p = Re(fracpartial textbfupartial t + textbfu cdot nabla textbfu) endalign with $Re$ being a dimensionless constant known as the Reynolds Number.



          This is very powerful as this allows us to reduce the physical intuition needed to understand the equations. Indeed, in the dimensionless formulation, we can view the Reynolds Number as the balancing term between the viscous and pressure terms compared to the inertial terms.



          We use mainly analytical tools such as asymptotic expansion, dominant balance, numerical solvers, and the weak formulation of the incompressible dimensionless Navier Stokes to approximate the flow. E.g., we don't use many physical properties about the fluid. Even in my graduate course, the only physics we really used were deriving the Navier Stokes equation.



          However, I'm sure there are many more sophisticated tools from analysis that one can use to study these PDEs in much more detail, but I have only taken up to Measure Theory and a basic introduction to PDE course. But, I hope this answers sheds some light on how mathematicians view Fluid Mechanics.



          For reference on the physics question, I have not taken any physics since high school physics so far. Sometimes it's a struggle to understand the underlying physics, but it is at an accessible level who puts in the effort.







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          edited Jul 21 at 6:08


























          answered Jul 21 at 6:02









          Raymond Chu

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              up vote
              1
              down vote













              Well, yes. Most (if not all) good mathematical arguments are a rigorous representation of physical intuition. And that is their power: the justification of this intuition via rigorous arguments on a formal basis.






              share|cite|improve this answer

























                up vote
                1
                down vote













                Well, yes. Most (if not all) good mathematical arguments are a rigorous representation of physical intuition. And that is their power: the justification of this intuition via rigorous arguments on a formal basis.






                share|cite|improve this answer























                  up vote
                  1
                  down vote










                  up vote
                  1
                  down vote









                  Well, yes. Most (if not all) good mathematical arguments are a rigorous representation of physical intuition. And that is their power: the justification of this intuition via rigorous arguments on a formal basis.






                  share|cite|improve this answer













                  Well, yes. Most (if not all) good mathematical arguments are a rigorous representation of physical intuition. And that is their power: the justification of this intuition via rigorous arguments on a formal basis.







                  share|cite|improve this answer













                  share|cite|improve this answer



                  share|cite|improve this answer











                  answered Jul 23 at 5:19









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